Methods for treating myeloproliferative disorders

ABSTRACT

In part, the present disclosure relates methods for treating, preventing, or reducing the severity of a myeloproliferative disorder (e.g., polycythemia vera, essential thrombocythemia, and myelofibrosis) or one or more complications of a myeloproliferative disorder. The present disclosure further relates methods for treating, preventing, or reducing the severity of a Janus kinase-associated disorder or one or more complications of a Janus kinase-associated disorder. In certain aspects the disclosure provides TβRII antagonists for treating, preventing, or reducing the severity of a myeloproliferative disorder (e.g., polycythemia vera, essential thrombocythemia, and myelofibrosis) or a Janus kinase-associated disorder or one or more complications of a myeloproliferative disorder or a Janus kinase-associated disorder.

RELATED APPLICATIONS

This application claims the benefit of priority from U.S. ProvisionalApplication No. 62/201,058, filed Aug. 4, 2015 and U.S. ProvisionalApplication No. 62/263,603, filed Dec. 4, 2015. The specifications ofeach of the foregoing applications are incorporated herein by referencein their entirety.

BACKGROUND OF THE INVENTION

Myeloproliferative disorders (MPDs), or neoplasms (MPNs), are a group ofconditions generally characterized by chronic increases in some or allof the blood cells (platelets, white blood cells, and red blood cells)[Talarico et al. (1998) Patient Care 30:37-57; Yavorkovsky et al. (2001)J Clin Oncol 19:3790-3792; and Campbell et at (2006) N Engl J Med355:2452-2-466]. This group of blood disorders includes polycythemiavera (PV), essential thrombocythemia (ET), myelofibrosis (e.g., primarymyelofibrosis, post-polycythemia vera myelofibrosis, and post-essentialthrombocythemia myelofibrosis), and chronic myeloid leukemia (CML). PVis characterized by increased production of all 3 types of blood cells,whereas ET is manifest in the elevation of platelets. Myelofibrosis (MF)is a disease in which fibrous (scar-like) tissues develop in the bonemarrow as a result of abnormal production of red cells, white cells,and/or platelets. CML is characterized by the increased and unregulatedgrowth of predominantly myeloid cells in the bone marrow and theaccumulation of these cells in the peripheral blood.

It is generally thought that MPDs arise from a transformation in ahematopoietic stem cell. Indeed, CML is now defined by its causativemolecular lesion, the BCR-ABL fusion gene, which most commonly resultsfrom the Philadelphia translocation (Ph). Accordingly, CML ischaracterized as a BCR-ABL positive (+) myeloproliferative disorder.Discovery of this defined molecular defect lead to the development ofthe drug imatinib mesylate (Gleevec; Novartis, Basel, Switzerland) totreat CML [Druker et al. (2001) N Engl J Med 344:1031-1037].

The other three myeloproliferative neoplasms (PV, ET, and MF) arecharacterized as BCR-ABL-negative myeloproliferative disorder. Recently,several groups identified a gain-of-function mutation of tyrosine kinaseJAK2 (JAK2V617F) as a major molecular defect in approximately 90%patients with PV, approximately 50% of patients with ET, andapproximately 50-60% of patients with MF [Baxter et al. (2005) Lancet365:1054-1061; James et al (2005) Nature 434:1144-1148; Kralovics (2005)N. Engl. J. Med. 352:1770-1790]. Interestingly, recent studies havedemonstrated that nearly 1% of blood samples collected from hospitalpatients test positive for the JAK2V617F mutation [Xu et al. (2007)Blood 109:339-342]. Most of these JAKV617F-positive patients do not meetthe criteria for diagnosis of MPDs but developed vascular diseases,including thrombosis, coronary heart disease, arteriosclerosis, cerebralischemia, and cerebral infarction at a higher rate thanJAKV617F-negative patients. These data suggest that MPDs and pre-MPDsconditions may represent a more profound public health problem thanoriginally anticipated and further emphasizes the pathologic importanceof the JAK2V617F as well as other Janus kinase mutations.

Allogeneic hematopoietic stem cell transplantation is the only knowncure for BCR-ABL-negative MPDs [Gupta et al. (2012) Blood120:1367-1379]. However, stem cell treatment-related mortality is highand only a minority of patients qualify for transplantation. While thedevelopment and use of JAK inhibitors represents a significanttherapeutic advancement, there are clear limitations to their use in thetreatment of BCR-ABL-negative MPDs. In particular, JAK inhibitors appearto be useful for reducing splenomegaly in myelofibrosis patients;however, their effects on the disease are otherwise largely palliative[Gupta et al. (2012) Blood 120:1367-1379]. In particular, JAK inhibitorshave little to no effect on many manifestations (complications) of thedisease including, for example, cytopenia, transfusion dependence,accelerated or blast phase disease, and fibrosis. Moreover, JAKinhibitors have been shown to promote or worsen thrombocytopenia,anemia, and neutropenia in some patients.

Thus, there is a high, unmet need for effective therapies treating MPDsand Janus kinase-associated disorders. Accordingly, it is an object ofthe present disclosure to provide methods for treating, preventing, orreducing the progression rate and/or severity of MPDs or Januskinase-associated disorders or one or more complications of MPDs orJanus kinase-associated disorders.

SUMMARY OF THE INVENTION

In part, the present disclosure relates to the discovery that a TGFβtype II receptor (TβRII) antagonist (inhibitor) can be used to treatmyelofibrosis, particularly ameliorating various complications of thedisease, including for example, fibrosis, splenomegaly, and inflammatorycomplications. In particular, the data presented herein shows that aTβRII polypeptide decreases fibrosis, splenomegaly, and inflammation ina JAK2V617F model of myelofibrosis. These data suggest that TβRIIantagonists may be used to treat myelofibrosis (e.g., primarymyelofibrosis, post-polycythemia vera myelofibrosis, and post-essentialthrombocytopenia myelofibrosis) as well as other myeloproliferativedisorders including, for example, polycythemia vera and essentialthrombocytopenia. Moreover, data from the JAK2V617F model suggests thatTβRII antagonists may be used treated Janus kinase-associated disorders,particularly disorders associated with elevated or constitutive Januskinase activity (e.g., elevated or constitutive JAK2 activity).Accordingly, in certain aspects, the disclosure relates to compositionsand methods for treating, preventing, or reducing the progression rateand/or severity of myeloproliferative disorders (e.g., myelofibrosis,polycythemia vera, and essential thrombocytopenia) or Januskinase-associated disorders one or more complications of amyeloproliferative disorder (e.g., fibrosis, splenomegaly, andinflammation) or Janus kinase-associated disorder, by administering to apatient in need thereof an effective amount of one or more TβRIIantagonists, optionally in combination of one or more other supportivetherapies or active agents for treating myeloproliferative disorders orJanus kinase-associated disorders. While TβRII polypeptides may affectmyeloproliferative disorders and Janus kinase-associated disordersthrough a mechanism other than TβRII antagonism [e.g., inhibition of oneor more of TGFβ1, TGFβ2, and TGFβ3 may be an indicator of the tendencyof an agent to inhibit the activities of a spectrum of additionalagents, including, perhaps, other members of the TGF-beta superfamily,and such collective inhibition may lead to the desired effect on, forexample, myeloproliferative disorders and Janus kinase-associateddisorders], the disclosure nonetheless demonstrates that desirabletherapeutic agents may be selected on the basis of TβRII antagonism.Therefore, while not wishing to be bound to a particular mechanism ofaction, it is expected that other TβRII antagonists [e.g., antagonistsof the TβRII receptor, antagonists of one or more TβRII-binding ligand(e.g., TGFβ1, TGFβ2, and TGFβ3), antagonists of one or moreTβRII-associated type I receptor (e.g., ALK5), antagonists of one ormore TβRII-associated co-receptor (betaglycan), antagonists of one ormore TβRII downstream signaling components (e.g., Smads), or combinationof such antagonists] will useful in the treatment of myeloproliferativedisorders or Janus kinase-associated disorders, particularly intreating, preventing, or reducing the progression rate and/or severityof one or more myeloproliferative disorder or Janus kinase-associateddisorder complications. Such agents are collectively referred to hereinas “TβRII antagonists” or “TβRII inhibitors”.

Accordingly, in certain aspects, the disclosure relates to methods fortreating a Janus kinase-associated disorder, comprising administering toa patient in need thereof an effective amount of a TβRII antagonist. Incertain aspects, the disclosure relates to methods for preventing aJanus kinase-associated disorder, comprising administering to a patientin need thereof an effective amount of a TβRII antagonist. In certainaspects, the disclosure relates to methods for reducing the progressionrate of a Janus kinase-associated disorder, comprising administering toa patient in need thereof an effective amount of a TβRII antagonist. Incertain aspects, the disclosure relates to methods for reducing theseverity of a Janus kinase-associated disorder, comprising administeringto a patient in need thereof an effective amount of a TβRII antagonist.In certain aspects, the disclosure relates to methods for treating oneor more complications of a Janus kinase-associated disorder, comprisingadministering to a patient in need thereof an effective amount of aTβRII antagonist. In certain aspects, the disclosure relates to methodsfor preventing one or more complications of a Janus kinase-associateddisorder, comprising administering to a patient in need thereof aneffective amount of a TβRII antagonist. In certain aspects, thedisclosure relates to methods for reducing the progression rate of oneor more complications of a Janus kinase-associated disorder, comprisingadministering to a patient in need thereof an effective amount of aTβRII antagonist. In certain aspects, the disclosure relates to methodsfor reducing the severity of one or more complications of a Januskinase-associated disorder, comprising administering to a patient inneed thereof an effective amount of a TβRII antagonist. In someembodiments, the disclosure relates to methods for treating, preventing,or reducing the progression rate and/or severity of one or morecomplications of a Janus kinase-associated disorder selected from thegroup consisting of: ineffective hematopoiesis, extramedullaryhematopoiesis (e.g., splenic extramedullary hematopoiesis, hepaticextramedullary hematopoiesis, pulmonary extramedullary hematopoiesis,and lymphatic extramedullary hematopoiesis), inflammatory complications,pancytopenia, fibrosis (e.g., bone marrow fibrosis, spleen fibrosis, andliver fibrosis), splenomegaly, hepatomegaly, thrombocytopenia, anemia,poikilocytosis, progressive hepatosplenomegaly, fatigue, weight loss,night sweats, fever, pruritus, bone pain, early satiety, abdominal painor discomfort, arthralgias, myalgias, parasthesias, cachexia, splenicinfarct, bleeding, inflammation, neutropenia, elevated cytokine levels,coagulopathy, IL-6-mediated inflammation or inflammatory complication,osteosclerosis, and osteomyelofibrosis. In some embodiments, a Januskinase-associated disorder is associated with one or moregain-of-function Janus kinase mutations. In some embodiments, a Januskinase-associated disorder is associated with one or moregain-of-function Janus kinase mutations in one or more Janus kinasesselected from the group consisting of: JAK1, JAK2, and JAK3. In someembodiments, a Janus kinase-associated disorder is associated with oneor more gain-of-function Janus kinase mutations in JAK2. In someembodiments, a Janus kinase-associated disorder is associated withelevated kinase activity (e.g., elevated kinase activity as compared to,for example, healthy subjects of the same age and sex) of one or moreJanus kinases. In some embodiments, a Janus kinase-associated disorderis associated with constitutive kinase activity of one or more Januskinases. In some embodiments, a Janus kinase-associated disorder isassociated with elevated or constitutive kinase activity of one or moreJanus kinases selected from the group consisting of: JAK1, JAK2, orJAK3. In some embodiments, a Janus kinase-associated disorder isassociated with elevated or constitutive kinase activity of JAK2. Insome embodiments, a Janus kinase-associated disorder is aJAK2-associated disorder. In some embodiments, a Janus kinase-associateddisorder is a JAK2V617F-associated disorder. In certain aspects, thedisclosure relates to methods of treating, preventing, or reducing theprogression rate and/or severity of a Janus kinase-associated disorderor one or more complications of a Janus kinase-associated disorderwherein the patient has myelofibrosis. In some embodiments, a patientwith a Janus kinase-associated disorder has primary myelofibrosis. Insome embodiments, a patient with a Janus kinase-associated disorder haspost-polycythemia vera myelofibrosis. In some embodiments, a patientwith a Janus kinase-associated disorder has post-essentialthrombocythemia myelofibrosis. In some embodiments, the disclosurerelates to methods for treating, preventing, or reducing the progressionrate and/or severity of one or more complications of a Januskinase-associated disorder in a patient having myelofibrosis selectedfrom the group consisting of: ineffective hematopoiesis, extramedullaryhematopoiesis (e.g., splenic extramedullary hematopoiesis, hepaticextramedullary hematopoiesis, pulmonary extramedullary hematopoiesis,and lymphatic extramedullary hematopoiesis), inflammatory complications,pancytopenia, fibrosis (e.g., bone marrow fibrosis, spleen fibrosis, andliver fibrosis), splenomegaly, hepatomegaly, thrombocytopenia, anemia,poikilocytosis, progressive hepatosplenomegaly, fatigue, weight loss,night sweats, fever, pruritus, bone pain, early satiety, abdominal painor discomfort, arthralgias, myalgias, parasthesias, cachexia, splenicinfarct, bleeding, inflammation, neutropenia, elevated cytokine levels,coagulopathy, IL-6-mediated inflammation or inflammatory complication,osteosclerosis, osteomyelofibrosis, and bleeding. In some embodiments, apatient with a Janus kinase-associated disorder has low riskmyelofibrosis according to the International Prognostic Scoring System(IPSS). In some embodiments, a patient with a Janus kinase-associateddisorder has intermediate-1 risk myelofibrosis according to the IPSS. Insome embodiments, a patient with a Janus kinase-associated disorder hasintermediate-2 risk myelofibrosis according to the IPSS. In someembodiments, a patient with a Janus kinase-associated disorder has highrisk myelofibrosis according to the IPSS. In some embodiments, a patientwith a Janus kinase-associated disorder has low risk myelofibrosisaccording to the dynamic IPSS (DIPSS). In some embodiments, a patientwith a Janus kinase-associated disorder has intermediate-1 riskmyelofibrosis according to the DIPSS. In some embodiments, a patientwith a Janus kinase-associated disorder has intermediate-2 riskmyelofibrosis according to the DIPSS. In some embodiments, a patientwith a Janus kinase-associated disorder has high risk myelofibrosisaccording to the DIPSS. In some embodiments, a patient with a Januskinase-associated disorder has low risk myelofibrosis according to theDIPSS-plus. In some embodiments, a patient with a Januskinase-associated disorder has intermediate-1 risk myelofibrosisaccording to the DIPSS-plus. In some embodiments, a patient with a Januskinase-associated disorder has intermediate-2 risk myelofibrosisaccording to the DIPSS-plus. In some embodiments, a patient with a Januskinase-associated disorder has high risk myelofibrosis according to theDIPSS-plus. In certain aspects, the disclosure relates to methods oftreating, preventing, or reducing the progression rate and/or severityof a Janus kinase-associated disorder or one or more complications of aJanus kinase-associated disorder wherein the patient has polycythemiavera. In some embodiments, the disclosure relates to method fortreating, preventing, or reducing the progression rate and/or severityof one or more complications of a Janus kinase-associated disorder in apatient having polycythemia vera selected from the group consisting of:fatigue, pruritus, night sweats, bone pain, fever, and weight loss,splenomegaly, hepatomegaly, abdominal pain, early satiety, nausea,abdominal organ compression, portal hypertension, vascular events,thromboembolic events, hemorrhages, thrombosis, macrovascularcomplications, headaches, dizziness, visual disturbances, distalparesthesia, acrocyanosis, erythromelalgia, excessive proliferation oferythroid cells, excessive proliferation of myeloid cells, excessiveproliferation of megakaryocytic cells, high red blood cell levels, highwhite blood cell levels, high platelet levels, elevated inflammatorycytokines, inflammatory complications, and IL-6-mediated inflammatorycomplications. In some embodiments, a patient with a Januskinase-associated disorder has low risk polycythemia vera. In someembodiments, a patient with a Janus kinase-associated disorder has lowrisk polycythemia vera and no history of thrombosis. In someembodiments, a patient with a Janus kinase-associated disorder has lowrisk polycythemia vera and has or previously had a history ofthrombosis. In some embodiments, a patient with a Januskinase-associated disorder has high risk polycythemia vera. In someembodiments, a patient with a Janus kinase-associated disorder has highrisk polycythemia vera and no history of thrombosis. In someembodiments, a patient with a Janus kinase-associated disorder has highrisk polycythemia vera and has or previously had a history ofthrombosis. In some embodiments, a patient with a Januskinase-associated disorder has high risk polycythemia vera and isrefractory to treatment with hydroxyurea. In some embodiments, a patientwith a Janus kinase-associated disorder has high risk polycythemia veraand is intolerant to treatment with hydroxyurea. In certain aspects, thedisclosure relates to methods of treating, preventing, or reducing theprogression rate and/or severity of a Janus kinase-associated disorderor one or more complications of a Janus kinase-associated disorderwherein the patient has essential thrombocythemia. In some embodiments,the disclosure relates to method for treating, preventing, or reducingthe progression rate and/or severity of one or more complications of aJanus kinase-associated disorder in a patient having essentialthrombocythemia selected from the group consisting of: thrombocytosis,low white blood cell counts, low hemoglobin levels, low lactatedehydrogenase (LDH) levels, fatigue, night sweats, nausea, numbness,visions disturbances, weight loss, microvascular complications,headache, chest pain, dizziness, erythromelalgia, splenomegaly,hepatomegaly, inflammatory complication, IL-6 inflammatory complication,elevated inflammatory cytokine levels, elevated IL-6 levels, andhemorrhage. In some embodiments, a patient with a Januskinase-associated disorder has low risk essential thrombocythemia. Insome embodiments, a patient with a Janus kinase-associated disorder haslow risk essential thrombocythemia and no history of thrombosis. In someembodiments, a patient with a Janus kinase-associated disorder has lowrisk essential thrombocythemia and has or previously had a history ofthrombosis. In some embodiments, a patient with a Januskinase-associated disorder has high risk essential thrombocythemia. Insome embodiments, a patient with a Janus kinase-associated disorder hashigh risk essential thrombocythemia and no history of thrombosis. Insome embodiments, a patient with a Janus kinase-associated disorder hashigh risk essential thrombocythemia and has or previously had a historyof thrombosis. In some embodiments, a patient with a Januskinase-associated disorder has high risk essential thrombocythemia andis refractory to treatment with hydroxyurea. In some embodiments, apatient with a Janus kinase-associated disorder has high risk essentialthrombocythemia and is intolerant to treatment with hydroxyurea. Incertain aspects, the disclosure relates to methods of treating,preventing, or reducing the progression rate and/or severity of a Januskinase-associated disorder or one or more complications of a Januskinase-associated disorder wherein the patient has fibrosis. In someembodiments, the disclosure relates to methods for treating, preventing,or reducing the progression rate and/or severity fibrosis in a Januskinase-associated disorder patient. In some embodiments, the disclosurerelates to methods for treating, preventing, or reducing the progressionrate and/or severity fibrosis in a Janus kinase-associated disorderpatient wherein the fibrosis is in one or more organs/tissues selectedfrom the group consisting of: spleen, liver, lung, lymph node, and bonemarrow. In some embodiments, the disclosure relates to methods fortreating, preventing, or reducing the rate progression and/or severityof spleen fibrosis in a Janus kinase-associated disorder patient. Insome embodiments, the disclosure relates to methods for treating,preventing, or reducing the rate progression and/or severity of bonemarrow fibrosis in a Janus kinase-associated disorder patient. In someembodiments, a patient with a Janus kinase-associated disorder has grade0 bone marrow fibrosis in accordance with the Bauermeister scoringsystem. In some embodiments, a patient with a Janus kinase-associateddisorder has grade 1 bone marrow fibrosis in accordance with theBauermeister scoring system. In some embodiments, a patient with a Januskinase-associated disorder has grade 2 bone marrow fibrosis inaccordance with the Bauermeister scoring system. In some embodiments, apatient with a Janus kinase-associated disorder has grade 3 bone marrowfibrosis in accordance with the Bauermeister scoring system. In someembodiments, a patient with a Janus kinase-associated disorder has grade4 bone marrow fibrosis in accordance with the Bauermeister scoringsystem. In some embodiments, methods of the disclosure relate toreducing bone marrow fibrosis by at least 1 grade in accordance with theBauermeister scoring system (e.g., grade reduction from 4 to 3, 4 to 2,4 to 1, 4 to 0, 3 to 2, 3 to 1, 3 to 0, 2 to 1, 2 to 0, or 1 to 0 bonemarrow fibrosis) in a patient with a Janus kinase-associated disorder.In some embodiments, methods of the disclosure relate to preventing ordelaying grade progression (e.g., preventing or delaying gradeprogression of bone marrow fibrosis from 0 to 1, 0 to 2, 0 to 3, 0 to 4,1 to 2, 1 to 3, 1 to 4, 2 to 3, 2 to 4, or 3 to 4) of bone marrowfibrosis according to the Bauermeister scoring system in a patient witha Janus kinase-associated disorder. In some embodiments, a patient witha Janus kinase-associated disorder has grade 1 bone marrow fibrosis inaccordance with the European consensus scoring system. In someembodiments, a patient with a Janus kinase-associated disorder has grade2 bone marrow fibrosis in accordance with the European consensus scoringsystem. In some embodiments, a patient with a Janus kinase-associateddisorder has grade 3 bone marrow fibrosis in accordance with theEuropean consensus scoring system. In some embodiments, methods of thedisclosure relate to reducing bone marrow fibrosis by at least 1 gradein accordance with the European consensus scoring system (e.g., gradereduction from 3 to 2, 3 to 1, 3 to 0, 2 to 1, 2 to 0, or 1 to 0 bonemarrow fibrosis) in a patient with a Janus kinase-associated disorder.In some embodiments, methods of the disclosure relate to preventing ordelaying grade progression (e.g., preventing or delaying gradeprogression of bone marrow fibrosis from 0 to 1, 0 to 2, 0 to 3, 1 to 2,1 to 3, 2 to 3) of bone marrow fibrosis according to the Europeanconsensus scoring system in a patient with a Janus kinase-associateddisorder. In some embodiments, the disclosure relates to methods forpreventing, or reducing the progression rate and/or severity fibrosis ina Janus kinase-associated disorder patient wherein the TβRII antagonistis administered prior to onset of fibrosis. In some embodiments, thedisclosure relates to methods for treating or reducing the progressionrate and/or severity fibrosis in a Janus kinase-associated disorderpatient wherein the TβRII antagonist is administered after the onset offibrosis. In certain aspects, the disclosure relates to methods oftreating, preventing, or reducing the progression rate and/or severityof a Janus kinase-associated disorder or one or more complications of aJanus kinase-associated disorder wherein the patient has organ/tissueenlargement (e.g., increased organ/tissue size and/or weight as comparedto, for example, healthy subjects of the same age and sex). In someembodiments, the disclosure relates to methods for treating, preventing,or reducing the progression rate and/or severity of organ/tissueenlargement in a Janus kinase-associated disorder patient. In someembodiments, the disclosure relates to methods for treating, preventing,or reducing the progression rate and/or severity of organ/tissueenlargement in a Janus kinase-associated disorder patient wherein theone or more organs/tissues are selected from the group consisting of:spleen, liver, lung(s), and lymph nodes. In some embodiments, thedisclosure relates to methods for treating, preventing, or reducing theprogression rate and/or severity of spleen enlargement in a Januskinase-associated disorder patient. In some embodiments, the disclosurerelates to methods for treating, preventing, or reducing the progressionrate and/or severity of liver enlargement in a Janus kinase-associateddisorder patient. In certain aspects, the disclosure relates to methodsof treating, preventing, or reducing the progression rate and/orseverity of a Janus kinase-associated disorder or one or morecomplications of a Janus kinase-associated disorder wherein the patienthas organ/tissue inflammation (e.g., increased organ/tissue inflammationas compared to, for example, healthy subjects of the same age and sex).In some embodiments, the disclosure relates to methods for treating,preventing, or reducing the progression rate and/or severity oforgan/tissue inflammation in a Janus kinase-associated disorder patient.In some embodiments, the disclosure relates to methods for treating,preventing, or reducing the progression rate and/or severity oforgan/tissue inflammation in a Janus kinase-associated disorder patientwherein the one or more organs/tissues is selected from the groupconsisting of: spleen, liver, lung(s), and lymph nodes. In someembodiments, the disclosure relates to methods for treating, preventing,or reducing the progression rate and/or severity of spleen inflammationin a Janus kinase-associated disorder patient. In some embodiments, thedisclosure relates to methods for treating, preventing, or reducing theprogression rate and/or severity of liver inflammation in a Januskinase-associated disorder patient. In certain aspects, the disclosurerelates to methods of treating, preventing, or reducing the progressionrate and/or severity of a Janus kinase-associated disorder or one ormore complications of a Janus kinase-associated disorder wherein thepatient has splenomegaly. In some embodiments, the disclosure relates tomethods for treating, preventing, or reducing the progression rateand/or severity of splenomegaly in a Janus kinase-associated disorderpatient. In certain aspects, the disclosure relates to methods oftreating, preventing, or reducing the progression rate and/or severityof a Janus kinase-associated disorder or one or more complications of aJanus kinase-associated disorder wherein the patient has hepatomegaly.In some embodiments, the disclosure relates to methods for treating,preventing, or reducing the progression rate and/or severity ofhepatomegaly in a Janus kinase-associated disorder patient. In certainaspects, the disclosure relates to methods of treating, preventing, orreducing the progression rate and/or severity of a Januskinase-associated disorder or one or more complications of a Januskinase-associated disorder wherein the patient has extramedullaryhematopoiesis. In some embodiments, the disclosure relates to methodsfor treating, preventing, or reducing the progression rate and/orseverity of extramedullary hematopoiesis in a Janus kinase-associateddisorder patient. In some embodiments, the disclosure relates to methodsfor treating, preventing, or reducing the progression rate and/orseverity of extramedullary hematopoiesis in a Janus kinase-associateddisorder patient wherein the one or more organs/tissues is selected fromthe group consisting of: spleen, liver, lymph nodes, and lung(s). Incertain aspects, the disclosure relates to methods of treating,preventing, or reducing the progression rate and/or severity of a Januskinase-associated disorder or one or more complications of a Januskinase-associated disorder wherein the patient has elevated inflammatorycytokine levels (e.g., elevated inflammatory cytokine levels as comparedto, for example, healthy subjects of the same age and sex). In someembodiments, the disclosure relates to methods for reducing inflammatorycytokine levels in one or more organs/tissues (e.g., serum cytokinelevels) in a Janus kinase-associated disorder patient. In someembodiments, the disclosure relates to methods for reducing IL-6 levelsin one or more organs/tissues in a Janus kinase-associated disorderpatient. In certain aspects, the disclosure relates to methods oftreating, preventing, or reducing the progression rate and/or severityof a Janus kinase-associated disorder or one or more complications of aJanus kinase-associated disorder wherein the patient has low red bloodcell levels (e.g., low red blood cell levels as compared to, forexample, healthy subjects of the same age and sex). In some embodiments,the disclosure relates to methods for increasing red blood cell levelsin a Janus kinase-associated disorder patient. In certain aspects, thedisclosure relates to methods of treating, preventing, or reducing theprogression rate and/or severity of a Janus kinase-associated disorderor one or more complications of a Janus kinase-associated disorderwherein the patient has low hemoglobin levels (e.g., low hemoglobinlevels as compared to, for example, healthy subjects of the same age andsex). In some embodiments, the disclosure relates to methods forincreasing hemoglobin levels in a Janus kinase-associated disorderpatient. In certain aspects, the disclosure relates to methods oftreating, preventing, or reducing the progression rate and/or severityof a Janus kinase-associated disorder or one or more complications of aJanus kinase-associated disorder wherein the patient has anemia. In someembodiments, the disclosure relates to methods for treating, preventing,or reducing the progression rate and/or severity of anemia in a Januskinase-associated disorder patient. In certain aspects, the disclosurerelates to methods of treating, preventing, or reducing the progressionrate and/or severity of a Janus kinase-associated disorder or one ormore complications of a Janus kinase-associated disorder wherein thepatient has been administered one or more blood cell transfusions priorto the start of TβRII antagonist treatment. In some embodiments, apatient with a Janus kinase-associated disorder is blood celltransfusion-dependent. In some embodiments, the disclosure relates tomethods for decreasing blood cell transfusion burden in a patient with aJanus kinase-associated disorder. In some embodiments, the disclosurerelates to methods for decreasing blood cell transfusion burden in apatient with a Janus kinase-associated disorder wherein the methoddecreases blood cell transfusion by greater than about 30%, 40%, 50%,60%, 70%, 80%, 90%, or 100% for 4 to 8 weeks relative to the equal timeprior to the start of TβRII antagonist treatment. In some embodiments,the disclosure relates to methods for decreasing blood cell transfusionburden in a patient with a Janus kinase-associated disorder wherein themethod decreases blood cell transfusion by greater than about 50% for 4to 8 weeks relative to the equal time prior to the start of TβRIIantagonist treatment. In certain aspects, a patient with a Januskinase-associated disorder has iron overload. In some embodiments, thedisclosure relates to methods for treating, preventing, or reducing theprogression rate and/or severity of iron overload in a Januskinase-associated disorder patient. In some embodiments, the disclosurerelates to methods for treating, preventing, or reducing the progressionrate and/or severity of spleen (splenic) iron overload in a Januskinase-associated disorder patient. In some embodiments, the disclosurerelates to methods for treating, preventing, or reducing the progressionrate and/or severity of liver (hepatic) iron overload in a Januskinase-associated disorder. In some embodiments, the disclosure relatesto methods for treating, preventing, or reducing the progression rateand/or severity of heart (cardiac) iron overload in a Januskinase-associated disorder. In certain aspects, the disclosure relatesto methods for reducing allele burden in a Janus kinase-associateddisorder patient. In some embodiments, the disclosure relates to methodsfor reducing allele burden of one or more Janus kinase alleles in aJanus kinase-associated disorder patient. In some embodiments, thedisclosure relates to methods for reducing allele burden of one or moreJanus kinase alleles selected from the group consisting of: JAK1, JAK2,and JAK3, in a Janus kinase-associated disorder patient. In someembodiments, the disclosure relates to methods for reducing alleleburden of one or more JAK2 alleles in a Janus kinase-associated disorderpatient. In some embodiments, the disclosure relates to methods forreducing allele burden of one or more Janus kinase alleles that areassociated with one or more mutations resulting in elevated (e.g.,elevated Janus kinase activity compared to, for example, healthysubjects of the same age and sex) or constitutive activation of one ormore Janus kinases in a Janus kinase-associated disorder patient. Insome embodiments, the disclosure relates to methods for reducing alleleburden of JAK2V617F in a Janus kinase-associated disorder patient. Incertain aspects, the disclosure relates to methods of treating,preventing, or reducing the progression rate and/or severity of a Januskinase-associated disorder or one or more complications of a Januskinase-associated disorder wherein the patient has been treated with aJanus kinase inhibitor. In some embodiments, the disclosure relates tomethods of treating, preventing, or reducing the progression rate and/orseverity of a Janus kinase-associated disorder or one or morecomplications of a Janus kinase-associated disorder wherein the patientis intolerant to treatment with a Janus kinase inhibitor (e.g.,ruxolitinib). In some embodiments, the disclosure relates to methods oftreating, preventing, or reducing the progression rate and/or severityof a Janus kinase-associated disorder or one or more complications of aJanus kinase-associated disorder wherein the patient is refractory totreatment with a Janus kinase inhibitor (e.g., ruxolitinib). In someembodiments, a patient with a Janus kinase-associated disorder has beentreated with a Janus kinase inhibitor that inhibits at least JAK2. Insome embodiments, a patient with a Janus kinase-associated disorder hasbeen treated with a Janus kinase inhibitor selected from the groupconsisting of: ruxolitinib, fedratinib (SAR302503), monoelotinib(CYT387), pacritinib, lestaurtinib, AZD-1480, BMS-911543, NS-018,LY2784544, SEP-701, XL019, and AT-9283. In some embodiments, a patientwith a Janus kinase-associated disorder has been treated withruxolitinib. In certain aspects, the disclosure relates to methods oftreating, preventing, or reducing the progression rate and/or severityof a Janus kinase-associated disorder or one or more complications of aJanus kinase-associated disorder wherein the patient has been treatedwith hydroxyurea. In some embodiments, the disclosure relates to methodsof treating, preventing, or reducing the progression rate and/orseverity of a Janus kinase-associated disorder or one or morecomplications of a Janus kinase-associated disorder wherein the patientis intolerant of treatment with hydroxyurea. In some embodiments, thedisclosure relates to methods of treating, preventing, or reducing theprogression rate and/or severity of a Janus kinase-associated disorderor one or more complications of a Janus kinase-associated disorderwherein the patient is refractory to treatment with hydroxyurea.

Accordingly, in certain aspects, the disclosure relates to methods fortreating a myeloproliferative disorder, comprising administering to apatient in need thereof an effective amount of a TβRII antagonist. Incertain aspects, the disclosure relates to methods for preventing amyeloproliferative disorder, comprising administering to a patient inneed thereof an effective amount of a TβRII antagonist. In certainaspects, the disclosure relates to methods for reducing the progressionrate of a myeloproliferative disorder, comprising administering to apatient in need thereof an effective amount of a TβRII antagonist. Incertain aspects, the disclosure relates to methods for reducing theseverity of a myeloproliferative disorder, comprising administering to apatient in need thereof an effective amount of a TβRII antagonist. Incertain aspects, the disclosure relates to methods for treating one ormore complications of a myeloproliferative disorder, comprisingadministering to a patient in need thereof an effective amount of aTβRII antagonist. In certain aspects, the disclosure relates to methodsfor preventing one or more complications of a myeloproliferativedisorder, comprising administering to a patient in need thereof aneffective amount of a TβRII antagonist. In certain aspects, thedisclosure relates to methods for reducing the progression rate of oneor more complications of a myeloproliferative disorder, comprisingadministering to a patient in need thereof an effective amount of aTβRII antagonist. In certain aspects, the disclosure relates to methodsfor reducing the severity of one or more complications of amyeloproliferative disorder, comprising administering to a patient inneed thereof an effective amount of a TβRII antagonist. In certainaspects, the disclosure relates to methods for treating myelofibrosis(e.g., primary myelofibrosis, post-polycythemia vera myelofibrosis, orpost-essential thrombocytopenia myelofibrosis), comprising administeringto a patient in need thereof an effective amount of a TβRII antagonist.In certain aspects, the disclosure relates to methods for preventingmyelofibrosis (e.g., primary myelofibrosis, post-polycythemia veramyelofibrosis, or post-essential thrombocytopenia myelofibrosis),comprising administering to a patient in need thereof an effectiveamount of a TβRII antagonist. In certain aspects, the disclosure relatesto methods for reducing the progression rate of myelofibrosis (e.g.,primary myelofibrosis, post-polycythemia vera myelofibrosis, orpost-essential thrombocytopenia myelofibrosis), comprising administeringto a patient in need thereof an effective amount of a TβRII antagonist.In certain aspects, the disclosure relates to methods for reducing theseverity of myelofibrosis (e.g., primary myelofibrosis,post-polycythemia vera myelofibrosis, or post-essential thrombocytopeniamyelofibrosis), comprising administering to a patient in need thereof aneffective amount of a TβRII antagonist. In certain aspects, thedisclosure relates to methods for treating one or more complications ofmyelofibrosis (e.g., primary myelofibrosis, post-polycythemia veramyelofibrosis, or post-essential thrombocytopenia myelofibrosis),comprising administering to a patient in need thereof an effectiveamount of a TβRII antagonist. In certain aspects, the disclosure relatesto methods for preventing one or more complications of myelofibrosis(e.g., primary myelofibrosis, post-polycythemia vera myelofibrosis, orpost-essential thrombocytopenia myelofibrosis), comprising administeringto a patient in need thereof an effective amount of a TβRII antagonist.In certain aspects, the disclosure relates to methods for reducing theprogression rate of one or more complications of myelofibrosis (e.g.,primary myelofibrosis, post-polycythemia vera myelofibrosis, orpost-essential thrombocytopenia myelofibrosis), comprising administeringto a patient in need thereof an effective amount of a TβRII antagonist.In certain aspects, the disclosure relates to methods for reducing theseverity of one or more complications of myelofibrosis (e.g., primarymyelofibrosis, post-polycythemia vera myelofibrosis, or post-essentialthrombocytopenia myelofibrosis), comprising administering to a patientin need thereof an effective amount of a TβRII antagonist. In certainaspects, the disclosure relates to methods for treating polycythemiavera, comprising administering to a patient in need thereof an effectiveamount of a TβRII antagonist. In certain aspects, the disclosure relatesto methods for preventing polycythemia vera, comprising administering toa patient in need thereof an effective amount of a TβRII antagonist. Incertain aspects, the disclosure relates to methods for reducing theprogression rate of polycythemia vera, comprising administering to apatient in need thereof an effective amount of a TβRII antagonist. Incertain aspects, the disclosure relates to methods for reducing theseverity of polycythemia vera, comprising administering to a patient inneed thereof an effective amount of a TβRII antagonist. In certainaspects, the disclosure relates to methods for treating one or morecomplications of polycythemia vera, comprising administering to apatient in need thereof an effective amount of a TβRII antagonist. Incertain aspects, the disclosure relates to methods for preventing one ormore complications of polycythemia vera, comprising administering to apatient in need thereof an effective amount of a TβRII antagonist. Incertain aspects, the disclosure relates to methods for reducing theprogression rate of one or more complications of polycythemia vera,comprising administering to a patient in need thereof an effectiveamount of a TβRII antagonist. In certain aspects, the disclosure relatesto methods for reducing the severity of one or more complications ofpolycythemia vera, comprising administering to a patient in need thereofan effective amount of a TβRII antagonist. In certain aspects, thedisclosure relates to methods for treating essential thrombocythemia,comprising administering to a patient in need thereof an effectiveamount of a TβRII antagonist. In certain aspects, the disclosure relatesto methods for preventing essential thrombocythemia, comprisingadministering to a patient in need thereof an effective amount of aTβRII antagonist. In certain aspects, the disclosure relates to methodsfor reducing the progression rate of essential thrombocythemia,comprising administering to a patient in need thereof an effectiveamount of a TβRII antagonist. In certain aspects, the disclosure relatesto methods for reducing the severity of essential thrombocythemia,comprising administering to a patient in need thereof an effectiveamount of a TβRII antagonist. In certain aspects, the disclosure relatesto methods for treating one or more complications of essentialthrombocythemia, comprising administering to a patient in need thereofan effective amount of a TβRII antagonist. In certain aspects, thedisclosure relates to methods for preventing one or more complicationsof essential thrombocythemia, comprising administering to a patient inneed thereof an effective amount of a TβRII antagonist. In certainaspects, the disclosure relates to methods for reducing the progressionrate of one or more complications of essential thrombocythemia,comprising administering to a patient in need thereof an effectiveamount of a TβRII antagonist. In certain aspects, the disclosure relatesto methods for reducing the severity of one or more complications ofessential thrombocythemia, comprising administering to a patient in needthereof an effective amount of a TβRII antagonist. In certain aspects,the disclosure relates to methods of treating, preventing, or reducingthe progression rate and/or severity of myelofibrosis or one or morecomplications of myelofibrosis, wherein the patient has low riskmyelofibrosis according to the International Prognostic Scoring System(IPSS). In certain aspects, the disclosure relates to methods oftreating, preventing, or reducing the progression rate and/or severityof myelofibrosis or one or more complications of myelofibrosis, whereinthe patient has intermediate-1 risk myelofibrosis according to the IPSS.In certain aspects, the disclosure relates to methods of treating,preventing, or reducing the progression rate and/or severity ofmyelofibrosis or one or more complications of myelofibrosis, wherein thepatient has intermediate-2 risk myelofibrosis according to the IPSS. Incertain aspects, the disclosure relates to methods of treating,preventing, or reducing the progression rate and/or severity ofmyelofibrosis or one or more complications of myelofibrosis, wherein thepatient has high-risk myelofibrosis risk myelofibrosis according to theIPSS. In certain aspects, the disclosure relates to methods of treating,preventing, or reducing the progression rate and/or severity ofmyelofibrosis or one or more complications of myelofibrosis, wherein thepatient has low risk myelofibrosis according to the dynamic IPSS(DIPSS). In certain aspects, the disclosure relates to methods oftreating, preventing, or reducing the progression rate and/or severityof myelofibrosis or one or more complications of myelofibrosis, whereinthe patient has intermediate-1 risk myelofibrosis according to theDIPSS. In certain aspects, the disclosure relates to methods oftreating, preventing, or reducing the progression rate and/or severityof myelofibrosis or one or more complications of myelofibrosis, whereinthe patient has intermediate-2 risk myelofibrosis according to theDIPSS. In certain aspects, the disclosure relates to methods oftreating, preventing, or reducing the progression rate and/or severityof myelofibrosis or one or more complications of myelofibrosis, whereinthe patient has high-risk myelofibrosis risk myelofibrosis according tothe DIPSS. In certain aspects, the disclosure relates to methods oftreating, preventing, or reducing the progression rate and/or severityof myelofibrosis or one or more complications of myelofibrosis, whereinthe patient has low risk myelofibrosis according to the DIPSS-plus. Incertain aspects, the disclosure relates to methods of treating,preventing, or reducing the progression rate and/or severity ofmyelofibrosis or one or more complications of myelofibrosis, wherein thepatient has intermediate-1 risk myelofibrosis according to theDIPSS-plus. In certain aspects, the disclosure relates to methods oftreating, preventing, or reducing the progression rate and/or severityof myelofibrosis or one or more complications of myelofibrosis, whereinthe patient has intermediate-2 risk myelofibrosis according to theDIPSS-plus. In certain aspects, the disclosure relates to methods oftreating, preventing, or reducing the progression rate and/or severityof myelofibrosis or one or more complications of myelofibrosis, whereinthe patient has high-risk myelofibrosis risk myelofibrosis according tothe DIPSS-plus. In certain aspects, a TβRII antagonists may be used toprevent or delay risk progression of myelofibrosis in accordance withany of the recognized risk stratification models for myelofibrosis(e.g., IPSS, DIPPS, and DIPPS-plus). For example, in some embodiments, aTβRII antagonist may be used to prevent or delay myelofibrosis riskprogression from low risk to intermediate-1 risk in accordance withIPSS, DIPPS, or DIPPS-plus. In other embodiments, a TβRII antagonist maybe used to prevent or delay myelofibrosis risk progression fromintermediate-1 risk to intermediate-2 risk in accordance with IPSS,DIPPS, or DIPPS-plus. In still other embodiments, a TβRII antagonist maybe used to prevent or delay myelofibrosis risk progression fromintermediate-2 risk to high risk in accordance with IPSS, DIPPS, orDIPPS-plus. In certain aspects, a TβRII antagonists may be used topromote or increase myelofibrosis risk regression in accordance with anyof the recognized risk stratification models for myelofibrosis (e.g.,IPSS, DIPPS, and DIPPS-plus). For example, in some embodiments, a TβRIIantagonist may be used to promote or increase myelofibrosis riskregression from high risk to intermediate-2 risk in accordance withIPSS, DIPPS, or DIPPS-plus. In other embodiments, a TβRII antagonist maybe used to promote or increase myelofibrosis risk regression fromintermediate-2 risk to intermediate-1 risk in accordance with IPSS,DIPPS, or DIPPS-plus. In still other embodiments, a TβRII antagonist maybe used to promote or increase myelofibrosis risk regression fromintermediate-1 risk to low risk in accordance with IPSS, DIPPS, orDIPPS-plus. In certain aspects, the disclosure relates to methods oftreating, preventing, or reducing the progression rate and/or severityof polycythemia vera or one or more complications of polycythemia vera,wherein the patient has low risk polycythemia vera. In some embodiments,the patient has low risk polycythemia vera and no history of thrombosis.In some embodiments, the patient has low risk polycythemia vera and hasor previously had thrombosis. In certain aspects, the disclosure relatesto methods of treating, preventing, or reducing the progression rateand/or severity of polycythemia vera or one or more complications ofpolycythemia vera, wherein the patient has high risk polycythemia vera.In some embodiments, the patient has high risk polycythemia vera and nohistory of thrombosis. In some embodiments, the patient has high riskpolycythemia vera and has or previously had thrombosis. In someembodiments, the patient has high risk polycythemia vera and isrefractory or intolerant to treatment with hydroxyurea. In certainaspects, the disclosure relates to methods of treating, preventing, orreducing the progression rate and/or severity of essentialthrombocytopenia or one or more complications of essentialthrombocytopenia, wherein the patient has low risk essentialthrombocytopenia. In some embodiments, the patient has low riskessential thrombocytopenia and no history of thrombosis. In someembodiments, the patient has low risk essential thrombocytopenia and hasor previously had thrombosis. In certain aspects, the disclosure relatesto methods of treating, preventing, or reducing the progression rateand/or severity of essential thrombocytopenia or one or morecomplications of essential thrombocytopenia, wherein the patient hashigh risk essential thrombocytopenia. In some embodiments, the patienthas high risk essential thrombocytopenia and no history of thrombosis.In some embodiments, the patient has high risk essentialthrombocytopenia and has or previously had thrombosis. In someembodiments, the patient has high risk essential thrombocytopenia and isrefractory or intolerant to treatment with hydroxyurea. In certainaspects, the disclosure relates to methods of using TβRII antagonists totreat, prevent, or reduce the progression rate and/or severity of amyeloproliferative disorder (e.g., myelofibrosis, polycythemia vera, andessential thrombocythemia) or one or more complications of amyeloproliferative disorder wherein the patient comprises one or moregene mutations or other molecular markers associated with amyeloproliferative disorder. For example, in some embodiments, a TβRIIantagonist may be used to treat, prevent, or reduce the progression rateand/or severity of a myeloproliferative disorder or one or morecomplications of a myeloproliferative disorder wherein the amyeloproliferative disorder is associated with one or more mutations inone or more genes selected from the group consisting of: IDH1, IDH2,EZH2, SRSF2, ASXL1, JAK1, JAK2, JAK3, TYK2, MPL, CALR, TET2, THPO, andLNK. In some embodiments, the myeloproliferative disorder is associatedwith one or more gene mutations in a Janus kinase (JAK) (e.g., JAK1,JAK2, and/or JAK3). In some embodiments, the myeloproliferative disorderis associated with one or more JAK2 mutations. In some embodiments, amyeloproliferative disorder is associated with one or moregain-of-function Janus kinase mutations. In some embodiments, amyeloproliferative disorder is associated with one or moregain-of-function Janus kinase mutations in one or more Janus kinasesselected from the group consisting of: JAK1, JAK2, and JAK3. In someembodiments, a myeloproliferative disorder is associated with one ormore gain-of-function Janus kinase mutations in JAK2. In someembodiments, a myeloproliferative disorder is associated with elevatedkinase activity (e.g., elevated kinase activity as compared to, forexample, healthy subjects of the same age and sex) of one or more Januskinases. In some embodiments, a myeloproliferative disorder isassociated with constitutive kinase activity of one or more Januskinases. In some embodiments, a myeloproliferative disorder isassociated with elevated or constitutive kinase activity of one or moreJanus kinases selected from the group consisting of: JAK1, JAK2, orJAK3. In some embodiments, a myeloproliferative disorder is associatedwith elevated or constitutive kinase activity of JAK2. In someembodiments, a myeloproliferative disorder is a JAK2-associateddisorder. In some embodiments, the myeloproliferative disorder isassociated with one or more genetic markers selected from the groupconsisting of: nullizygosity for JAK2 46/1 haplotype, JAK2V617F,CALR+ASXL1−, CALR−ASKL1+, CALR+ASKL1+, and CALR−ASKL1−. In someembodiments, the myeloproliferative disorder is associated with theJAK2V617F mutation. In some embodiments, the method reduces themyeloproliferative disease-associated allele burden in the patient. Insome embodiments, the method reduces the allele burden of one or moreJAK2 mutations. In some embodiments, the method reduces the alleleburden of JAK2V617F. In some embodiments, the method reduces alleleburden of one or more mutations in one or more genes selected from thegroup consisting of: IDH1, IDH2, EZH2, SRSF2, ASXL1, JAK1, JAK2, JAK3,TYK2, MPL, CALR, TET2, THPO, and LNK. In some embodiments, the methodreduces allele burden of one or more genetic markers selected from thegroup consisting of: nullizygosity for JAK2 46/1 haplotype, CALR+ASXL1−,CALR−ASKL1+, CALR+ASKL1+, and CALR−ASKL1−. In certain aspects, thedisclosure relates to methods of using a TβRII antagonist to treat,prevent, or reduce the progression rate and/or severity of amyeloproliferative disorder (e.g., myelofibrosis, polycythemia vera, andessential thrombocythemia) or one or more complications of amyeloproliferative disorder wherein the myelofibrosis is associated withone or more elevated serum markers selected from the group consistingof: increased serum IL-8 levels, increased serum IL-2R levels, andincreased serum free light chain levels. In certain aspects, thedisclosure relates to methods of using a TβRII antagonist to treat,prevent, or reduce the progression rate and/or severity of amyeloproliferative disorder (e.g., myelofibrosis, polycythemia vera, andessential thrombocythemia) or one or more complications of amyeloproliferative disorder wherein the patient has been treated with aJanus kinase inhibitor. In some embodiments, the patient has beentreated with a JAK2 inhibitor. In some embodiments, the patient has beentreated with a Janus kinase inhibitor selected from the group consistingof: ruxolitinib, fedratinib (SAR302503), monoelotinib (CYT387),pacritinib, lestaurtinib, AZD-1480, BMS-911543, NS-018, LY2784544,SEP-701, XL019, and AT-9283. In some embodiments, the patient has beentreated with ruxolitinib. In some embodiments, a TβRII antagonist may beused to treat, prevent, or reduce the progression rate and/or severityof a myeloproliferative disorder or one or more complications of amyeloproliferative disorder wherein the patient is intolerant of a Januskinase inhibitor. In some embodiments, a TβRII antagonist may be used totreat, prevent, or reduce the progression rate and/or severity of amyeloproliferative disorder or one or more complications of amyeloproliferative disorder wherein the patient has an inadequateresponse to a Janus kinase inhibitor. In certain aspects, the disclosurerelates to methods of using a TβRII antagonist to treat, prevent, orreduce the progression rate and/or severity of a myeloproliferativedisorder (e.g., myelofibrosis, polycythemia vera, and essentialthrombocythemia) or one or more complications of a myeloproliferativedisorder wherein the patient has been treated with hydroxyurea. In someembodiments, a TβRII antagonist may be used to treat, prevent, or reducethe progression rate and/or severity of a myeloproliferative disorder orone or more complications of a myeloproliferative disorder wherein thepatient is intolerant of hydroxyurea. In some embodiments, a TβRIIantagonist may be used to treat, prevent, or reduce the progression rateand/or severity of a myeloproliferative disorder or one or morecomplications of a myeloproliferative disorder wherein the patient hasan inadequate response to hydroxyurea.

As described herein myeloproliferative disorders are clonal neoplasticdiseases of hematopoiesis that are associated with various clinicalcomplications which may manifest during disease progression in apatient. The examples of the disclosure demonstrate that a TβRIIantagonist may be used to mitigate a number of these clinicalcomplications, indicating that TβRII antagonists may be used to morebroadly treat various complications of myeloproliferative disorders(e.g., myelofibrosis, polycythemia vera, and essential thrombocytopenia)as opposed to many of the current myeloproliferative disorder therapies,which only treat one or a limited number of complications of thedisease. Therefore, in certain aspects, a TβRII antagonist may be usedto treat, prevent, or reduce the progression rate and/or severity of oneor more constitutional symptoms (e.g., fatigue, weight loss, nightsweats, fever, pruritus, early satiety, abdominal pain or discomfort,arthralgias, myalgias, paresthesias, nausea, abdominal organcompression, headache, and cachexia) in a patient with amyeloproliferative disorder (e.g., myelofibrosis, polycythemia vera, andessential thrombocytopenia). In certain aspects, a TβRII antagonist maybe used to treat, prevent, or reduce the progression rate and/orseverity of bone pain in a patient with a myeloproliferative disorder(e.g., myelofibrosis, polycythemia vera, and essentialthrombocytopenia). In certain aspects, a TβRII antagonist may be used totreat, prevent, or reduce the progression rate and/or severity of visiondisturbances in a patient with a myeloproliferative disorder (e.g.,myelofibrosis, polycythemia vera, and essential thrombocytopenia). Incertain aspects, the disclosure relates to methods of treating,preventing, or reducing the progression rate and/or severity of amyeloproliferative disorder (e.g., myelofibrosis, polycythemia vera, andessential thrombocytopenia) or one or more complications of amyeloproliferative disorder wherein the patient has fibrosis. In someembodiments, the disclosure relates to methods for treating, preventing,or reducing the progression rate and/or severity fibrosis in amyeloproliferative disorder patient. In some embodiments, the disclosurerelates to methods for treating, preventing, or reducing the progressionrate and/or severity fibrosis in a myeloproliferative disorder patientwherein the fibrosis is in one or more organs/tissues selected from thegroup consisting of: spleen, liver, lung, lymph node, and bone marrow.In some embodiments, the disclosure relates to methods for treating,preventing, or reducing the rate progression and/or severity of spleenfibrosis in a myeloproliferative disorder patient. In some embodiments,the disclosure relates to methods for treating, preventing, or reducingthe rate progression and/or severity of bone marrow fibrosis in amyeloproliferative disorder patient. In some embodiments, a patient witha myeloproliferative disorder has grade 0 bone marrow fibrosis inaccordance with the Bauermeister scoring system. In some embodiments, apatient with a myeloproliferative disorder has grade 1 bone marrowfibrosis in accordance with the Bauermeister scoring system. In someembodiments, a patient with a myeloproliferative disorder has grade 2bone marrow fibrosis in accordance with the Bauermeister scoring system.In some embodiments, a patient with a myeloproliferative disorder hasgrade 3 bone marrow fibrosis in accordance with the Bauermeister scoringsystem. In some embodiments, a patient with a myeloproliferativedisorder has grade 4 bone marrow fibrosis in accordance with theBauermeister scoring system. In some embodiments, methods of thedisclosure relate to reducing bone marrow fibrosis by at least 1 gradein accordance with the Bauermeister scoring system (e.g., gradereduction from 4 to 3, 4 to 2, 4 to 1, 4 to 0, 3 to 2, 3 to 1, 3 to 0, 2to 1, 2 to 0, or 1 to 0 bone marrow fibrosis) in a patient with amyeloproliferative disorder. In some embodiments, methods of thedisclosure relate to preventing or delaying grade progression (e.g.,preventing or delaying grade progression of bone marrow fibrosis from 0to 1, 0 to 2, 0 to 3, 0 to 4, 1 to 2, 1 to 3, 1 to 4, 2 to 3, 2 to 4, or3 to 4) of bone marrow fibrosis according to the Bauermeister scoringsystem in a patient with a myeloproliferative disorder. In someembodiments, a patient with a myeloproliferative disorder has grade 1bone marrow fibrosis in accordance with the European consensus scoringsystem. In some embodiments, a patient with a myeloproliferativedisorder has grade 2 bone marrow fibrosis in accordance with theEuropean consensus scoring system. In some embodiments, a patient with amyeloproliferative disorder has grade 3 bone marrow fibrosis inaccordance with the European consensus scoring system. In someembodiments, methods of the disclosure relate to reducing bone marrowfibrosis by at least 1 grade in accordance with the European consensusscoring system (e.g., grade reduction from 3 to 2, 3 to 1, 3 to 0, 2 to1, 2 to 0, or 1 to 0 bone marrow fibrosis) in a patient with amyeloproliferative disorder. In some embodiments, methods of thedisclosure relate to preventing or delaying grade progression (e.g.,preventing or delaying grade progression of bone marrow fibrosis from 0to 1, 0 to 2, 0 to 3, 1 to 2, 1 to 3, 2 to 3) of bone marrow fibrosisaccording to the European consensus scoring system in a patient with amyeloproliferative disorder. In some embodiments, the disclosure relatesto methods for preventing, or reducing the progression rate and/orseverity fibrosis in a myeloproliferative wherein the TβRII antagonistis administered prior to onset of fibrosis. In some embodiments, thedisclosure relates to methods for treating or reducing the progressionrate and/or severity fibrosis in a myeloproliferative disorder patientwherein the TβRII antagonist is administered after the onset offibrosis. In certain aspects, a TβRII antagonist may be used to treat,prevent, or reduce the progression rate and/or severity of organ/tissue(e.g., spleen, liver, lymph nodes, and lungs) inflammation (e.g.,increased inflammation as compared to, for example, healthy subjects ofthe same age and sex) and/or enlargement (e.g., increased organ/tissuesize and/or weight as compared to, for example, healthy subjects of thesame age and sex) in a patient with a myeloproliferative disorder (e.g.,myelofibrosis, polycythemia vera, and essential thrombocytopenia). Insome embodiments, a TβRII antagonist may be used to treat, prevent, orreduce the progression rate and/or severity of splenomegaly in a patientwith a myeloproliferative disorder (e.g., myelofibrosis, polycythemiavera, and essential thrombocytopenia). In some embodiments, a TβRIIantagonist may be used to treat, prevent, or reduce the progression rateand/or severity of hepatomegaly in a patient with a myeloproliferativedisorder (e.g., myelofibrosis, polycythemia vera, and essentialthrombocytopenia). In certain aspects, a TβRII antagonist may be used totreat, prevent, or reduce the progression rate and/or severity ofsplenic infarct in a patient with a myeloproliferative disorder (e.g.,myelofibrosis, polycythemia vera, and essential thrombocytopenia). Incertain aspects, a TβRII antagonist may be used to treat, prevent, orreduce the progression rate and/or severity of one or more inflammatorycomplications in a patient with a myeloproliferative disorder (e.g.,myelofibrosis, polycythemia vera, and essential thrombocytopenia). Insome embodiments, a TβRII antagonist may be used to reduce inflammatorycytokine levels in a patient with a myeloproliferative disorder (e.g.,myelofibrosis, polycythemia vera, and essential thrombocytopenia). Insome embodiments, a TβRII antagonist may be used to reduce IL6 levels ina patient with a myeloproliferative disorder (e.g., myelofibrosis,polycythemia vera, and essential thrombocytopenia). In some embodiments,a TβRII antagonist may be used to treat, prevent, or reduce theprogression rate and/or severity of one or more IL6-associatedcomplications in a patient with a myeloproliferative disorder (e.g.,myelofibrosis, polycythemia vera, and essential thrombocytopenia). Incertain aspects, a TβRII antagonist may be used to treat, prevent, orreduce the progression rate and/or severity of extramedullaryhematopoiesis (e.g., splenic extramedullary hematopoiesis, hepaticextramedullary hematopoiesis, pulmonary extramedullary hematopoiesis,and lymphatic extramedullary hematopoiesis) in a patient with amyeloproliferative disorder (e.g., myelofibrosis, polycythemia vera, andessential thrombocytopenia). In certain aspects, a TβRII antagonist maybe used to treat, prevent, or reduce the progression rate and/orseverity of vascular complications in a patient with amyeloproliferative disorder (e.g., myelofibrosis, polycythemia vera, andessential thrombocytopenia). In certain aspects, a TβRII antagonist maybe used to treat, prevent, or reduce the progression rate and/orseverity of thrombosis in a patient with a myeloproliferative disorder(e.g., myelofibrosis, polycythemia vera, and essentialthrombocytopenia). In certain aspects, a TβRII antagonist may be used totreat, prevent, or reduce the progression rate and/or severity ofhemorrhaging in a patient with a myeloproliferative disorder (e.g.,myelofibrosis, polycythemia vera, and essential thrombocytopenia). Incertain aspects, a TβRII antagonist may be used to treat, prevent, orreduce the progression rate and/or severity of ineffectiveerythropoiesis in a patient with a myeloproliferative disorder (e.g.,myelofibrosis). In certain aspects, a TβRII antagonist may be used totreat, prevent, or reduce the progression rate and/or severity ofineffective erythropoiesis in a patient with a myeloproliferativedisorder (e.g., myelofibrosis). In certain aspects, TβRII antagonist maybe used to treat, prevent, or reduce the progression rate and/orseverity of pancytopenia in a patient with a myeloproliferative disorder(e.g., myelofibrosis). In certain aspects, a TβRII antagonist may beused to treat, prevent, or reduce the progression rate and/or severityof pancytopenia in a patient with a myeloproliferative disorder (e.g.,myelofibrosis). In certain aspects, a TβRII antagonist may be used totreat, prevent, or reduce the progression rate and/or severity ofthrombocytopenia in a patient with a myeloproliferative disorder (e.g.,myelofibrosis). In certain aspects, a TβRII antagonist may be used totreat, prevent, or reduce the progression rate and/or severity of anemiain a patient with a myeloproliferative disorder (e.g., myelofibrosis).In certain aspects, a TβRII antagonist may be used to treat, prevent, orreduce the progression rate and/or severity of poikilocytosis in apatient with a myeloproliferative disorder (e.g., myelofibrosis). Incertain aspects, a TβRII antagonist may be used to treat, prevent, orreduce the progression rate and/or severity of neutropenia in a patientwith a myeloproliferative disorder (e.g., myelofibrosis). In certainaspects, a TβRII antagonist may be used to treat, prevent, or reduce theprogression rate and/or severity of osteosclerosis in a patient with amyeloproliferative disorder (e.g., myelofibrosis). In certain aspects, aTβRII antagonist may be used to treat, prevent, or reduce theprogression rate and/or severity of osteomyelofibrosis in a patient witha myeloproliferative disorder (e.g., myelofibrosis). In certain aspects,a TβRII antagonist may be used to treat, prevent, or reduce theprogression rate and/or severity of excessive proliferation of one ormore blood cells (e.g., erythroid cells, myeloid cells, andmegakaryocytic cells) in a patient with a myeloproliferative disorder(e.g., polycythemia vera). In certain aspects, a TβRII antagonist may beused to reduce levels of red blood cells in a patient with amyeloproliferative disorder (e.g., polycythemia vera). In certainaspects, a TβRII antagonist may be used to reduce levels of white bloodcells in a patient with a myeloproliferative disorder (e.g.,polycythemia vera). In certain aspects, a TβRII antagonist may be usedto reduce levels of platelets in a patient with a myeloproliferativedisorder (e.g., polycythemia vera and essential thrombocythemia). Incertain aspects, the disclosure relates to increasing red blood celllevels in a patient with a myeloproliferative disorder (e.g.,myelofibrosis) by administering an effective amount of a TβRIIantagonist. In certain aspects, disclosure relates to increasinghemoglobin levels in a patient with a myeloproliferative disorder (e.g.,myelofibrosis) by administering an effective amount of a TβRIIantagonist. In certain aspects, a patient with a myeloproliferativedisorder (e.g., myelofibrosis) to be treated in accordance with themethods described herein has anemia. In some embodiments, a TβRIIantagonist may be used to treat, prevent, or reduce the progression rateand/or severity of anemia in a patient with a myeloproliferativedisorder (e.g., myelofibrosis). In certain aspects, the disclosurerelates to methods using a TβRII antagonist to treat, prevent, or reducethe progression rate and/or severity of a myeloproliferative disorder(e.g., myelofibrosis) or a complication of a myeloproliferative disorderin a patient that has been administered one or more blood celltransfusions (whole or red blood cell transfusions). In someembodiments, the disclosure relates to methods using a TβRII antagonistto treat, prevent, or reduce the progression rate and/or severity of amyeloproliferative disorder (e.g., myelofibrosis) or a complication of amyeloproliferative disorder in patient that is blood celltransfusion-dependent. In certain aspects, a TβRII antagonist may beused to decrease (reduce) blood cell transfusion burden in a patientwith a myeloproliferative disorder (e.g., myelofibrosis). For example, aTβRII antagonist may be used to decrease blood cell transfusion bygreater than about 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 100% for 4 to 8weeks relative to the equal time prior to the start of the TβRIIantagonist treatment in a patient with a myeloproliferative disorder(e.g., myelofibrosis). In some embodiments, a TβRII antagonist may beused to decrease blood cell transfusion by greater than about 50% for 4to 8 weeks relative to the equal time prior to the start of the TβRIIantagonist treatment in a patient with a myeloproliferative disorder(e.g., myelofibrosis). In certain aspects, a TβRII antagonist may beused to decrease iron overload in a patient with a myeloproliferativedisorder (e.g., myelofibrosis). For example, a TβRII antagonist may beused to decrease iron overload in an organ and/or tissue in a patientwith a myeloproliferative disorder (e.g., myelofibrosis). In someembodiments, a TβRII antagonist may be used to decrease iron overload inthe spleen of a patient with a myeloproliferative disorder (e.g.,myelofibrosis). In some embodiments, a TβRII antagonist may be used todecrease iron overload in the liver of a patient with amyeloproliferative disorder (e.g., myelofibrosis). In some embodiments,a TβRII antagonist may be used to decrease iron overload in the heart ofa patient with a myeloproliferative disorder (e.g., myelofibrosis).

In part, the present disclosure relates to methods of treating,preventing, or reducing the severity or progression rate of a JAK2kinase-associated disorder, comprising administering to a patient inneed thereof an effective amount of a TβRII antagonist. In someembodiments, the patient has is a JAK2V617F mutation-associateddisorder. In certain aspects, the disclosure relates to methods fortreating, preventing, or reducing the progression rate and/or severityof one or more complications of a JAK2 kinase-associated disordercomprising administering to a patient in need thereof an effectiveamount of a TβRII antagonist. For example, in some embodiments, the oneor more complications of a JAK2 kinase-associated disorder are selectedfrom the group consisting of: ineffective hematopoiesis, extramedullaryhematopoiesis (e.g., splenic extramedullary hematopoiesis, hepaticextramedullary hematopoiesis, pulmonary extramedullary hematopoiesis,and lymphatic extramedullary hematopoiesis), inflammatory complications,pancytopenia, fibrosis (e.g., bone marrow fibrosis, spleen fibrosis, andliver fibrosis), splenomegaly, hepatomegaly, thrombocytopenia, anemia,poikilocytosis, progressive hepatosplenomegaly, fatigue, weight loss,night sweats, fever, pruritus, bone pain, early satiety, abdominal painor discomfort, arthralgias, myalgias, parasthesias, cachexia, splenicinfarct, bleeding, inflammation, neutropenia, elevated cytokine levels,coagulopathy, IL-6-mediated inflammation or inflammatory complication,osteosclerosis, and osteomyelofibrosis. In certain aspects, thedisclosure relates to methods of using a TβRII antagonist to treat,prevent, or reduce the progression rate and/or severity of a JAK2kinase-associated disorder or one or more complications of a JAK2kinase-associated disorder (e.g., a JAK2 gain-of-function associateddisorder) wherein the patient further comprises one or more additionalgene mutations or other molecular markers associated with amyeloproliferative disorder. For example, in some embodiments, a TβRIIantagonist may be used to treat, prevent, or reduce the progression rateand/or severity of a JAK2 kinase-associated disorder or one or morecomplications of a JAK2 kinase-associated disorder wherein the amyeloproliferative disorder is further associated with one or moremutations in one or more genes selected from the group consisting of:IDH1, IDH2, EZH2, SRSF2, ASXL1, TYK2, MPL, CALR, TET2, THPO, and LNK. Insome embodiments, the a JAK2 kinase-associated disorder is furtherassociated with one or more genetic markers selected from the groupconsisting of: nullizygosity for JAK2 46/1 haplotype, JAK2V617F,CALR+ASXL1−, CALR−ASKL1+, CALR+ASKL1+, and CALR−ASKL1−. In someembodiments, the method reduces the JAK2-associated disorder alleleburden in the patient. In some embodiments, the method reduces theallele burden of one or more JAK2 mutations. In some embodiments, themethod reduces the allele burden of JAK2V617F. In some embodiments, themethod reduces allele burden of one or more mutations in one or moregenes selected from the group consisting of: IDH1, IDH2, EZH2, SRSF2,ASXL1, JAK1, JAK3, TYK2, MPL, CALR, TET2, THPO, and LNK. In someembodiments, the method reduces allele burden of one or more geneticmarkers selected from the group consisting of: nullizygosity for JAK246/1 haplotype, CALR+ASXL1−, CALR-ASKL1+, CALR+ASKL1+, and CALR-ASKL1−.In certain aspects, the disclosure relates to methods of using a TβRIIantagonist to treat, prevent, or reduce the progression rate and/orseverity of a JAK2 kinase-associated disorder or one or morecomplications of a JAK2 kinase-associated disorder wherein the a JAK2kinase-associated disorder is further associated with one or moreelevated serum markers selected from the group consisting of: increasedserum IL-8 levels, increased serum IL-2R levels, and increased serumfree light chain levels. In certain aspects, the disclosure relates tomethods of using a TβRII antagonist to treat, prevent, or reduce theprogression rate and/or severity of a JAK2 kinase-associated disorder orone or more complications of a JAK2 kinase-associated disorder whereinthe patient has been treated with a Janus kinase inhibitor. In someembodiments, the patient has been treated with a JAK2 inhibitor. In someembodiments, the patient has been treated with a Janus kinase inhibitorselected from the group consisting of: ruxolitinib, fedratinib(SAR302503), monoelotinib (CYT387), pacritinib, lestaurtinib, AZD-1480,BMS-911543, NS-018, LY2784544, SEP-701, XL019, and AT-9283. In someembodiments, the patient has been treated with ruxolitinib. In someembodiments, a TβRII antagonist may be used to treat, prevent, or reducethe progression rate and/or severity of a JAK2 kinase-associateddisorder or one or more complications of a JAK2 kinase-associateddisorder wherein the patient is intolerant of a Janus kinase inhibitor.In some embodiments, a TβRII antagonist may be used to treat, prevent,or reduce the progression rate and/or severity of a JAK2kinase-associated disorder or one or more complications of a JAK2kinase-associated disorder wherein the patient has an inadequateresponse to a Janus kinase inhibitor. In certain aspects, the disclosurerelates to methods of using a JAK2 kinase-associated disorder to treat,prevent, or reduce the progression rate and/or severity of a JAK2kinase-associated disorder or one or more complications of a JAK2kinase-associated disorder wherein the patient has been treated withhydroxyurea. In some embodiments, a TβRII antagonist may be used totreat, prevent, or reduce the progression rate and/or severity of a JAK2kinase-associated disorder or one or more complications of a JAK2kinase-associated disorder wherein the patient is intolerant ofhydroxyurea. In some embodiments, a TβRII antagonist may be used totreat, prevent, or reduce the progression rate and/or severity of a JAK2kinase-associated disorder or one or more complications of a JAK2kinase-associated disorder wherein the patient has an inadequateresponse to hydroxyurea.

In any of the methods and uses described herein, a patient with amyeloproliferative disorder (e.g., myelofibrosis, polycythemia vera, andessential thrombocytopenia) and/or a patient with a Januskinase-associated disorder (e.g., a JAK2 kinase-associated disorder) mayfurther be administered one or more additional active agents and/orsupportive therapies (in addition to administration of one or more TβRIIantagonists) for treating, preventing, or reducing, the progression rateand/or severity of a myeloproliferative disorder and/or a Januskinase-associated disorder or one or more complications of amyeloproliferative disorder and/or a Janus kinase-associated disorder.For example, in some embodiments, a patient may be further administeredone or more supportive therapies or active agents selected from thegroup consisting of: blood transfusion (whole blood or red blood celltransfusion), erythropoiesis-stimulating agents [e.g., ESAs such aserythropoietin (EPO) and derivatives thereof], androgens (e.g.,testosterone enanthate and fluoxymesterone), prednisone, danazol,thalidomide, prednisone, lenalidomide, iron-chelating agents,deferoxamine, deferiprone, deferasirox, hydroxyurea, cladribineruxolitinib, SAR302503, CYT387, pacritinib, AZD-1480, BMS-911543,NS-018, LY2784544, lestaurtinib, SEP-701, AT-9283, Janus kinaseinhibitors (e.g., inhibitors of one or more of JAK1, JAK2, and JAK3),splenectomy, radiotherapy, aspirin, immunomodulating drugs, PI3K/mTORinhibitors, epigenetic factors modulators, pomalidonmide, rapamycin,sirolimus, deforolimus, everolimus, temsirolimus, NVP-BEZ235, BGT226,SF1126, PK1-587, INK128, AZD8055, AZD2014, histone deacetylaseinhibitors, givinostat, panobinostat, pracinostat, corticosteroids,gamma-interferon, cyclophosphamide, azathioprine, methotrexate,penicillamine, cyclosporine, colchicine, antithymocyte globulin,mycophenolate mofetil, hydroxychloroquine, calcium channel blockers,nifedipine, angiotensin converting enzyme inhibitors, para-aminobenzoicacid, dimethyl sulfoxide, interleukin-5 (IL-5) inhibitors, pan caspaseinhibitors, lectins, colchicine, azathioprine, cyclophosphamide,prednisone, thalidomide, pentoxifylline, and theophylline.

In certain aspects, the disclosure relates to methods for treating,preventing, or reducing the progression rate and/or severity of amyeloproliferative disorder (e.g., myelofibrosis, polycythemia vera, andessential thrombocytopenia) and/or a patient with a Januskinase-associated disorder (e.g., a JAK2 kinase-associated disorder) orone or more complications of a myeloproliferative disorder and/or aJanus kinase-associated disorder, comprising administering to a patientin need thereof: a) a Janus kinase inhibitor; and b) a TβRIIantagonists, wherein the Janus kinase inhibitor and TβRII antagonist areadministered in an effective amount. In some embodiments, a TβRIIantagonist is administered prior to treatment with the Janus kinaseinhibitor. In other embodiments, a TβRII antagonist is administeredafter treatment with the Janus kinase inhibitor. In even otherembodiments, a TβRII antagonist is administered concurrently with theJanus kinase inhibitor. A Janus kinase inhibitor to be used inaccordance with the methods described herein may be an agent thatinhibits one or more Janus kinases selected from the group consistingof: JAK1, JAK2, and JAK3. For example, a Janus kinase inhibitor may bean agent that inhibits signaling of one or more of JAK1, JAK2, and JAK3in a cell-based assay. In some embodiments, a Janus kinase inhibitor tobe used in accordance with the methods described herein is selected fromthe group consisting of: ruxolitinib, fedratinib (SAR302503),monoelotinib (CYT387), pacritinib, lestaurtinib, AZD-1480, BMS-911543,NS-018, LY2784544, SEP-701, XL019, and AT-9283. In some preferredembodiments, a Janus kinase inhibitor to be used in accordance with themethods described herein is ruxolitinib.

In certain aspects, a TβRII antagonist, or combination of antagonists,to be used in accordance with methods and uses described herein is anagent that inhibits at least TGFβ1 (e.g., a TGFβ1 antagonist). Effectson TGFβ1 inhibition may be determined, for example, using a cell-basedassay including those described herein (e.g., Smad signaling assay).Therefore, in some embodiments, a TβRII antagonist, or combination ofantagonists, of the disclosure may bind to at least TGFβ1. Ligandbinding activity may be determined, for example, using a bindingaffinity assay including those described herein. In some embodiments, aTβRII antagonist, or combination of antagonists, of the disclosure bindsto at least TGFβ1 with a K_(D) of at least 1×10⁻⁷M (e.g., at least1×10⁻⁸M, at least 1×10⁻⁹M, at least 1×10⁻¹⁰ M, at least 1×10⁻¹¹M, or atleast 1×10⁻¹²M). As described herein, various TβRII antagonists thatinhibit TGFβ1 can be used in accordance with the methods and usesdescribed herein including, for example, ligand traps (e.g., TβRIIpolypeptides and variants thereof), antibodies, small molecules,nucleotide sequences, and combinations thereof. In certain embodiments,a TβRII antagonist, or combination of antagonists, that inhibits TGFβ1may further inhibit one or more of: TGFβ2, TGFβ3, TβRII, ALK5, andbetaglycan. In some embodiments, a TβRII antagonist, or combination ofantagonists, that inhibits TGFβ1 further inhibits TGFβ3. In someembodiments, a TβRII antagonist, or combination of antagonists, thatinhibits TGFβ1 does not inhibit or does not substantially inhibit TGFβ2.In some embodiments, a TβRII antagonist, or combination of antagonists,that inhibits TGFβ1 further inhibits TGFβ3 but does not inhibit or doesnot substantially inhibit TGFβ2.

In certain aspects, a TβRII antagonist, or combination of antagonists,to be used in accordance with methods and uses described herein is anagent that inhibits at least TGFβ2 (e.g., a TGFβ2 antagonist). Effectson TGFβ2 inhibition may be determined, for example, using a cell-basedassay including those described herein (e.g., Smad signaling assay).Therefore, in some embodiments, a TβRII antagonist, or combination ofantagonists, of the disclosure may bind to at least TGFβ2. Ligandbinding activity may be determined, for example, using a bindingaffinity assay including those described herein. In some embodiments, aTβRII antagonist, or combination of antagonists, of the disclosure bindsto at least TGFβ2 with a K_(D) of at least 1×10⁻⁷ M (e.g., at least1×10⁻⁸ M, at least 1×10⁻⁹ M, at least 1×10⁻¹⁰ M, at least 1×10⁻¹¹ M, orat least 1×10⁻¹² M). As described herein, various TβRII antagonists thatinhibit TGFβ2 can be used in accordance with the methods and usesdescribed herein including, for example, ligand traps (e.g., TβRIIpolypeptides and variants thereof), antibodies, small molecules,nucleotide sequences, and combinations thereof. In certain embodiments,a TβRII antagonist, or combination of antagonists, that inhibits TGFβ2may further inhibit one or more of: TGFβ1, TGFβ3, TβRII, ALK5, andbetaglycan.

In certain aspects, a TβRII antagonist, or combination of antagonists,to be used in accordance with methods and uses described herein is anagent that inhibits at least TGFβ3 (e.g., a TGFβ3 antagonist). Effectson TGFβ3 inhibition may be determined, for example, using a cell-basedassay including those described herein (e.g., Smad signaling assay).Therefore, in some embodiments, a TβRII antagonist, or combination ofantagonists, of the disclosure may bind to at least TGFβ3. Ligandbinding activity may be determined, for example, using a bindingaffinity assay including those described herein. In some embodiments, aTβRII antagonist, or combination of antagonists, of the disclosure bindsto at least TGFβ3 with a K_(D) of at least 1×10⁻⁷ M (e.g., at least1×10⁻⁸M, at least 1×10⁻⁹M, at least 1×10⁻¹⁰ M, at least 1×10⁻¹¹ M, or atleast 1×10⁻¹² M). As described herein, various TβRII antagonists thatinhibit TGFβ3 can be used in accordance with the methods and usesdescribed herein including, for example, ligand traps (e.g., TβRIIpolypeptides and variants thereof), antibodies, small molecules,nucleotide sequences, and combinations thereof. In certain embodiments,a TβRII antagonist, or combination of antagonists, that inhibits TGFβ3may further inhibit one or more of: TGFβ1, TGFβ2, TβRII, ALK5, andbetaglycan. In some embodiments, a TβRII antagonist, or combination ofantagonists, that inhibits TGFβ3 further inhibits TGFβ1. In someembodiments, a TβRII antagonist, or combination of antagonists, thatinhibits TGFβ3 does not inhibit or does not substantially inhibit TGFβ2.In some embodiments, a TβRII antagonist, or combination of antagonists,that inhibits TGFβ3 further inhibits TGFβ1 but does not inhibit or doesnot substantially inhibit TGFβ2.

In certain aspects, a TβRII antagonist, or combination of antagonists,to be used in accordance with methods and uses described herein is anagent that inhibits at least TβRII (e.g., a TβRII receptor antagonist).Effects on TβRII inhibition may be determined, for example, using acell-based assay including those described herein (e.g., Smad signalingassay). Therefore, in some embodiments, a TβRII antagonist, orcombination of antagonists, of the disclosure may bind to at leastTβRII. Ligand binding activity may be determined, for example, using abinding affinity assay including those described herein. In someembodiments, a TβRII antagonist, or combination of antagonists, of thedisclosure binds to at least TβRII with a K_(D) of at least 1×10⁻⁷ M(e.g., at least 1×10⁻⁸M, at least 1×10⁻⁹M, at least 1×10⁻¹⁰ M, at least1×10⁻¹¹ M, or at least 1×10⁻¹² M). As described herein, various TβRIIantagonists that inhibit TβRII can be used in accordance with themethods and uses described herein including, for example, ligand traps(e.g., TβRII polypeptides and variants thereof), antibodies, smallmolecules, nucleotide sequences, and combinations thereof. In certainembodiments, a TβRII antagonist, or combination of antagonists, thatinhibits TβRII may further inhibit one or more of: TGFβ1, TGFβ2, TGFβ3,ALK5, and betaglycan. In some embodiments, a TβRII antagonist, orcombination of antagonists, that inhibits TβRII does not inhibit or doesnot substantially inhibit TGFβ2.

In certain aspects, a TβRII antagonist, or combination of antagonists,to be used in accordance with methods and uses described herein is anagent that inhibits at least ALK5 (e.g., a ALK5 antagonist). Effects onALK5 inhibition may be determined, for example, using a cell-based assayincluding those described herein (e.g., Smad signaling assay).Therefore, in some embodiments, a TβRII antagonist, or combination ofantagonists, of the disclosure may bind to at least ALK5. Ligand bindingactivity may be determined, for example, using a binding affinity assayincluding those described herein. In some embodiments, an ALK5antagonist, or combination of antagonists, of the disclosure binds to atleast ALK5 with a K_(D) of at least 1×10⁻⁷ M (e.g., at least 1×10⁻⁸ M,at least 1×10⁻⁹ M, at least 1×10⁻¹⁰ M, at least 1×10⁻¹¹ M, or at least1×10⁻¹² M). As described herein, various TβRII antagonists that inhibitALK5 can be used in accordance with the methods and uses describedherein including, for example, ligand traps (e.g., TβRII polypeptidesand variants thereof), antibodies, small molecules, nucleotidesequences, and combinations thereof. In certain embodiments, a TβRIIantagonist, or combination of antagonists, that inhibits ALK5 mayfurther inhibit one or more of: TGFβ1, TGFβ2, TGFβ3, TβRII, andbetaglycan. In some embodiments, a TβRII antagonist, or combination ofantagonists, that inhibits ALK5 does not inhibit or does notsubstantially inhibit TGFβ2.

In certain aspects, a TβRII antagonist, or combination of antagonists,to be used in accordance with methods and uses described herein is anagent that inhibits at least betaglycan (e.g., a betaglycan antagonist).Effects on betaglycan inhibition may be determined, for example, using acell-based assay including those described herein (e.g., Smad signalingassay). Therefore, in some embodiments, a TβRII antagonist, orcombination of antagonists, of the disclosure may bind to at leastbetaglycan. Ligand binding activity may be determined, for example,using a binding affinity assay including those described herein. In someembodiments, a betaglycan antagonist, or combination of antagonists, ofthe disclosure binds to at least betaglycan with a K_(D) of at least1×10⁻⁷ M (e.g., at least 1×10⁻⁸ M, at least 1×10⁻⁹ M, at least 1×10⁻¹⁰M, at least 1×10⁻¹¹ M, or at least 1×10⁻¹² M). As described herein,various TβRII antagonists that inhibit betaglycan can be used inaccordance with the methods and uses described herein including, forexample, ligand traps (e.g., TβRII polypeptides and variants thereof),antibodies, small molecules, nucleotide sequences, and combinationsthereof. In certain embodiments, a TβRII antagonist, or combination ofantagonists, that inhibits betaglycan may further inhibit one or moreof: TGFβ1, TGFβ2, TGFβ3, TβRII, and ALK5. In some embodiments, a TβRIIantagonist, or combination of antagonists, that inhibits betaglycan doesnot inhibit or does not substantially inhibit TGFβ2.

In certain aspects, the disclosure provides TβRII polypeptides and theuse of such TβRII polypeptides as selective antagonists for TGFβ1 and/orTGFβ3. As described herein, polypeptides comprising part or all of theTβRII extracellular domain (ECD), with or without additional mutations,bind to and/or inhibit TGFβ1 and/or TGFβ3 with varying affinities. Thus,in certain aspects, the disclosure provides TβRII polypeptides for usein selectively inhibiting TGFβ superfamily associated disorders.

In certain aspects, the disclosure provides polypeptides comprisingmutations and/or truncations in the extracellular domain of TβRII. Incertain aspects, the disclosure provides a TβRII fusion polypeptidecomprising a first amino acid sequence from the extracellular domain ofTβRII and a heterologous amino acid sequence, wherein the first aminoacid sequence comprises or consists of an amino acid sequence at least80%, at least 85%, at least 90%, at least 95%, at least 96%, at least97%, at least 98%, at least 99% identical or identical to a) a sequencebeginning at any of positions 23 to 35 of SEQ ID NO: 5 and ending at anyof positions 153 to 159 of SEQ ID NO: 5 orb) a sequence beginning at anyof positions 23 to 60 of SEQ ID NO: 6 and ending at any of positions 178to 184 of SEQ ID NO: 6.

In certain aspects the disclosure provides polypeptides comprising awild-type or altered and/or truncated extracellular domain of TβRIIfused to at least a portion of the Fc domain of a human IgG2. Thus incertain aspects, the disclosure provides a TβRII fusion polypeptidecomprising a first amino acid sequence from the extracellular domain ofTβRII and a heterologous amino acid sequence, wherein the first aminoacid sequence comprises or consists of an amino acid sequence at least80%, at least 85%, at least 90%, at least 95%, at least 96%, at least97%, at least 98%, at least 99% identical or identical to a) a sequencebeginning at any of positions 23 to 35 of SEQ ID NO: 5 and ending at anyof positions 153 to 159 of SEQ ID NO: 5 orb) a sequence beginning at anyof positions 23 to 60 of SEQ ID NO: 6 and ending at any of positions 178to 184 of SEQ ID NO: 6, and wherein the polypeptide comprises a secondpolypeptide sequence that comprises at least a constant domain of ahuman IgG2 and may optionally comprise or consist of an amino acidsequence that is at least 80%, at least 85%, at least 90%, at least 95%,at least 96%, at least 97%, at least 98%, at least 99% identical to SEQID NO: 19, and wherein an linker is optionally positioned between thefirst polypeptide and the second polypeptide. An example of the isprovided as SEQ ID NO: 50 and is encoded by the nucleic acid sequence ofSEQ ID NO: 51. In certain embodiments, the disclosure providespolypeptides with an amino acid sequence that comprises or consists ofan amino acid sequence that is at least 80%, 85%, 90%, 95%, 96%, 97%.98%, 99% or 100% identical to the amino acid sequence of SEQ ID NO: 50.In certain embodiments, the disclosure provides polypeptides that areencoded by a nucleic acid sequence that comprises or consists of anucleic acid sequence that is at least 80%, 85%, 90%, 95%, 96%, 97%,98%, 99% or 100% identical to the nucleic acid sequence of SEQ ID NO:51.

In certain aspects the disclosure provides polypeptides comprising awild-type or altered and/or truncated extracellular domain of TβRIIfused to at least a portion of the Fc domain of a human IgG1, IgG3, orIgG4.

In certain aspects the disclosure provides polypeptides comprising awild-type or altered and/or truncated extracellular domain of TβRIIfused to at least a portion of the Fc domain of a human IgG1. Thus incertain aspects, the disclosure provides a TβRII fusion polypeptidecomprising a first amino acid sequence from the extracellular domain ofTβRII and a heterologous amino acid sequence, wherein the first aminoacid sequence comprises, consisting essentially of, or consists of anamino acid sequence at least 80%, at least 85%, at least 90%, at least95%, at least 96%, at least 97%, at least 98%, at least 99% identical oridentical the amino acid sequence of SEQ ID NO: 13, and wherein anlinker is optionally positioned between the first polypeptide and thesecond polypeptide. An example of another TβRII fusion polypeptideprovided as SEQ ID NO: 101 and is encoded by the nucleic acid sequenceof SEQ ID NO: 102. In certain embodiments, the disclosure providespolypeptides with an amino acid sequence that comprises, consistsessentially of, or consists of an amino acid sequence that is at least80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% identical to the aminoacid sequence of SEQ ID NO: 101. In certain embodiments, the disclosureprovides polypeptides with an amino acid sequence that comprises,consists essentially of, or consists of an amino acid sequence that isat least 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% identical to theamino acid sequence of SEQ ID NO: 103. In certain embodiments, thedisclosure provides an amino acid sequence that is at least 80%, 85%,90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% identical toan amino acid sequence that begins at any one of amino acids 25-46(e.g., 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,41, 42, 43, 44, 45, or 46) of SEQ ID NO: 101 and ends and any one ofamino acids 170-186 (e.g., 170, 171, 172, 173, 174, 175, 176, 177, 178,179, 180, 181, 182, 183, 184, 185, or 186) of SEQ ID NO: 101. In certainembodiments, the disclosure provides polypeptides that are encoded by anucleic acid sequence that comprises or consists of a nucleic acidsequence that is at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100%identical to the nucleic acid sequence of SEQ ID NO: 102. In certainembodiments, the disclosure provides a nucleic acid sequence thatcomprises or consists of a nucleic acid sequence that is at least 80%,85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% identical to the nucleic acidsequence of SEQ ID NO: 102.

In some embodiments, the first amino acid sequence comprises or consistsof the sequence beginning at position 23 of SEQ ID NO: 5 and ending atposition 159 of SEQ ID NO: 5. In some embodiments, the first amino acidsequence comprises or consists of the sequence beginning at position 29of SEQ ID NO: 5 and ending at position 159 of SEQ ID NO: 5. In someembodiments, the first amino acid sequence comprises or consists of thesequence beginning at position 35 of SEQ ID NO: 5 and ending at position159 of SEQ ID NO: 5. In some embodiments, the first amino acid sequencecomprises or consists of the sequence beginning at position 23 of SEQ IDNO: 5 and ending at position 153 of SEQ ID NO: 5. In some embodiments,the first amino acid sequence comprises or consists of the sequencebeginning at position 29 of SEQ ID NO: 5 and ending at position 153 ofSEQ ID NO: 5. In some embodiments, the first amino acid sequencecomprises or consists of the sequence beginning at position 35 of SEQ IDNO: 5 and ending at position 153 of SEQ ID NO: 5.

In some embodiments, the first amino acid sequence comprises or consistsof the sequence beginning at position 23 of SEQ ID NO: 6 and ending atpositions 184 of SEQ ID NO: 6. In some embodiments, the first amino acidsequence comprises or consists of the sequence beginning at position 29of SEQ ID NO: 6 and ending at position 184 of SEQ ID NO: 6. In someembodiments, the first amino acid sequence comprises or consists of thesequence beginning at position 23 of SEQ ID NO: 6 and ending at position178 of SEQ ID NO: 6. In some embodiments, the first amino acid sequencecomprises or consists of the sequence beginning at position 29 of SEQ IDNO: 6 and ending at position 178 of SEQ ID NO: 6.

In some embodiments, the first amino acid sequence comprises or consistsof a sequence that has a D at the position corresponding to position 36of SEQ ID NO: 47 and/or a K at the position corresponding to position 76of SEQ ID NO: 47.

In certain aspects, the disclosure provides a TβRII fusion polypeptidecomprising a first amino acid sequence at least 80%, at least 85%, atleast 90%, at least 95%, at least 96%, at least 97%, at least 98%, atleast 99% identical or identical to the sequence of SEQ ID NO: 7 or SEQID NO: 13, or active fragment thereof, and a second heterologousportion, wherein the first amino acid sequence has a D at the positioncorresponding to position 36 of SEQ ID NO: 47 and/or a K at the positioncorresponding to position 76 of SEQ ID NO: 47.

In some embodiments, the first amino acid sequence comprises anN-terminal truncation of 1-12 amino acids corresponding to amino acids1-12 of SEQ ID NO: 7 or 1-37 amino acids corresponding to amino acids1-37 of SEQ ID NO: 13. In some embodiments, the first amino acidsequence comprises an N-terminal truncation of 6 amino acidscorresponding to amino acids 1-6 of SEQ ID NO: 7 or SEQ ID NO: 13. Insome embodiments, the first amino acid sequence comprises an N-terminaltruncation of 12 amino acids corresponding to amino acids 1-12 of SEQ IDNO: 7 or 37 amino acids corresponding to amino acids 1-37 of SEQ ID NO:13. In some embodiments, the first amino acid sequence comprises aC-terminal truncation of 1-6 amino acids corresponding to amino acids137-132 of SEQ ID NO: 7 or amino acids 162-157 of SEQ ID NO: 13. In someembodiments, the first amino acid sequence comprises a C-terminaltruncation of 6 amino acids corresponding to amino acids 132-137 of SEQID NO: 7 or amino acids 157-162 of SEQ ID NO: 13. In some embodiments,the first amino acid sequence comprises an insertion corresponding toSEQ ID NO: 18 between the residues corresponding to positions 117 and118 of SEQ ID NO: 47.

In some embodiments, the heterologous portion comprises one or morepolypeptide portions that enhance one or more of: in vivo stability, invivo half-life, uptake/administration, tissue localization ordistribution, formation of protein complexes, and/or purification. Insome embodiments, the heterologous portion comprises a polypeptideportion selected from: an immunoglobulin Fc domain and a serum albumin.In a further embodiment, the immunoglobulin Fc domain is joined to theTβRII polypeptide by a linker.

In some embodiments, the polypeptide includes one or more modified aminoacid residues selected from: a glycosylated amino acid, a PEGylatedamino acid, a farnesylated amino acid, an acetylated amino acid, abiotinylated amino acid, an amino acid conjugated to a lipid moiety, andan amino acid conjugated to an organic derivatizing agent. In someembodiments, the polypeptide is glycosylated.

In certain aspects, the disclosure provides a TβRII fusion polypeptidecomprising a first amino acid sequence consisting of a portion of theextracellular domain of TβRII that comprises an amino acid sequence thatis at least 80%, at least 85%, at least 90%, or at least 95% identicalto an amino acid sequence selected from SEQ ID NOs: 7-17 and 47-49, anda second heterologous portion. In certain aspects, the disclosureprovides a TβRII fusion polypeptide comprising a first amino acidsequence consisting of a portion of the extracellular domain of TβRIIthat comprises an amino acid sequence that is at least 96% identical toan amino acid sequence selected from SEQ ID NOs: 7-17 and 47-49, and asecond heterologous portion. In certain aspects, the disclosure providesa TβRII fusion polypeptide comprising a first amino acid sequenceconsisting of a portion of the extracellular domain of TβRII thatcomprises an amino acid sequence that is at least 97% identical to anamino acid sequence selected from SEQ ID NOs: 7-17 and 47-49, and asecond heterologous portion. In certain aspects, the disclosure providesa TβRII fusion polypeptide comprising a first amino acid sequenceconsisting of a portion of the extracellular domain of TβRII thatcomprises an amino acid sequence that is at least 98% identical to anamino acid sequence selected from SEQ ID NOs: 7-17 and 47-49, and asecond heterologous portion. In certain aspects, the disclosure providesa TβRII fusion polypeptide comprising a first amino acid sequenceconsisting of a portion of the extracellular domain of TβRII thatcomprises an amino acid sequence that is at least 99% identical to anamino acid sequence selected from SEQ ID NOs: 7-17 and 47-49, and asecond heterologous portion. In certain aspects, the disclosure providesa TβRII fusion polypeptide comprising a first amino acid sequenceconsisting of a portion of the extracellular domain of TβRII thatcomprises an amino acid sequence is an amino acid sequence selected fromSEQ ID NOs: 7-17 and 47-49 and a second heterologous portion.

In certain aspects, the disclosure provides a polypeptide comprising orconsisting of an amino acid sequence that is at least 80%, at least 85%,at least 90%, or at least 95% identical to an amino acid sequenceselected from SEQ ID NOs: 25, 27, 29, 31, 33, 35, 37, 39, 41 and 43 orthe portion thereof with the leader sequence removed, e.g., apolypeptide comprising or consisting of an amino acid sequence that isat least 80%, at least 85%, at least 90%, or at least 95% identical toan amino acid sequence selected from SEQ ID NOs: 53, 54, 55, 56, 57, 58,59, 60, 61, and 62. In certain aspects, the disclosure provides apolypeptide comprising or consisting of an amino acid sequence that isat least 96% identical to an amino acid sequence selected from SEQ IDNOs: 25, 27, 29, 31, 33, 35, 37, 39, 41 and 43 or the portion thereofwith the leader sequence removed, e.g., a polypeptide comprising orconsisting of an amino acid sequence that is at least 96% identical toan amino acid sequence selected from SEQ ID NOs: 53, 54, 55, 56, 57, 58,59, 60, 61, and 62. In certain aspects, the disclosure provides apolypeptide comprising or consisting of an amino acid sequence that isat least 97% identical to an amino acid sequence selected from SEQ IDNOs: 25, 27, 29, 31, 33, 35, 37, 39, 41 and 43 or the portion thereofwith the leader sequence removed, e.g., a polypeptide comprising orconsisting of an amino acid sequence that is at least 97% identical toan amino acid sequence selected from SEQ ID NOs: 53, 54, 55, 56, 57, 58,59, 60, 61, and 62. In certain aspects, the disclosure provides apolypeptide comprising or consisting of an amino acid sequence that isat least 98% identical to an amino acid sequence selected from SEQ IDNOs: 25, 27, 29, 31, 33, 35, 37, 39, 41 and 43 or the portion thereofwith the leader sequence removed, e.g., a polypeptide comprising orconsisting of an amino acid sequence that is at least 98% identical toan amino acid sequence selected from SEQ ID NOs: 53, 54, 55, 56, 57, 58,59, 60, 61, and 62. In certain aspects, the disclosure provides apolypeptide comprising or consisting of an amino acid sequence that isat least 99% identical to an amino acid sequence selected from SEQ IDNOs: 25, 27, 29, 31, 33, 35, 37, 39, 41 and 43 or the portion thereofwith the leader sequence removed, e.g., a polypeptide comprising orconsisting of an amino acid sequence that is at least 99% identical toan amino acid sequence selected from SEQ ID NOs: 53, 54, 55, 56, 57, 58,59, 60, 61, and 62. In certain aspects, the disclosure provides apolypeptide comprising or consisting of an amino acid sequence selectedfrom SEQ ID NOs: 25, 27, 29, 31, 33, 35, 37, 39, 41 and 43 or theportion thereof with the leader sequence removed, e.g., a polypeptidecomprising or consisting of an amino acid sequence selected from SEQ IDNOs: 53, 54, 55, 56, 57, 58, 59, 60, 61, and 62.

In certain aspects, the disclosure provides a TβRII polypeptidecomprising of an amino acid sequence encoded by a nucleic acid thathybridizes under stringent conditions to a complement of a nucleotidesequence selected from SEQ ID NOs: 26, 28, 30, 32, 34, 36, 38, 40, 42and 44.

In each of the foregoing, the TβRII polypeptide may be selected that itdoes not include a full-length TβRII ECD. A TβRII polypeptide may beused as a monomeric protein or in a dimerized form. A TβRII polypeptidemay also be fused to a second polypeptide portion to provide improvedproperties, such as increased half-life or greater ease of production orpurification. A fusion may be direct or a linker may be inserted betweenthe TβRII polypeptide and any other portion. A linker may be structuredor unstructured and may consist of 1, 2, 3, 4, 5, 10, 15, 20, 30, 50 ormore amino acids, optionally relatively free of secondary structure.

In some embodiments, a TβRII polypeptide of the disclosure has aglycosylation pattern characteristic of expression of the polypeptide inCHO cells.

In some embodiments, the disclosure provides a homodimer comprising twoTβRII polypeptides of the disclosure.

In some embodiments, the disclosure provides an isolated polynucleotidecomprising a coding sequence for the TβRII polypeptides of thedisclosure. In some embodiments, the disclosure provides a recombinantpolynucleotide comprising a promoter sequence operably linked to theisolated polynucleotide. In some embodiments, the disclosure provides acell transformed with an isolated polynucleotide or a recombinantpolynucleotide of the disclosure. In some embodiments, the cell is amammalian cell. In some embodiments, the cell is a CHO cell or a humancell. In some embodiments, the cell is an HEK-293 cell.

In certain aspects, the disclosure provides a pharmaceutical preparationcomprising the TβRII polypeptides or homodimers of the disclosure and apharmaceutically acceptable excipient.

In certain aspects, a TβRII antagonist is an antibody, or combination ofantibodies. In certain aspects, the antibody binds to at least TβRII. Insome embodiments a TβRII antagonist antibody that binds to TβRIIinhibits TβRII signaling, optionally as measured in a cell-based assaysuch as those described herein. In some embodiments, a TβRII antagonistantibody that binds to TβRII inhibits one or more TGF-beta superfamilyligands, TGFβ superfamily type I receptors, or TGFβ superfamilyco-receptors from binding to TβRII. In some embodiments, a TβRIIantagonist antibody that binds to TβRII inhibits one or more TGF-betasuperfamily ligands from binding to TβRII selected from the groupconsisting of: TGFβ1, TGFβ2, and TGFβ3. In certain aspects, the antibodybinds to at least ALK5. In some embodiments a TβRII antagonist antibodythat binds to ALK5 inhibits ALK5 signaling, optionally as measured in acell-based assay such as those described herein. In some embodiments, aTβRII antagonist antibody that binds to ALK5 inhibits one or moreTGF-beta superfamily ligands, TGFβ superfamily type II receptors, orTGFβ superfamily co-receptors from binding to ALK5. In some embodimentsa TβRII antagonist antibody that binds to ALK5 inhibits one or moreTGF-beta superfamily ligands from binding to ALK5 selected from thegroup consisting of: TGFβ1, TGFβ2, and TGFβ3. In certain aspects, theantibody binds to at least betaglycan. In some embodiments a TβRIIantagonist antibody that binds to betaglycan inhibits betaglycansignaling, optionally as measured in a cell-based assay such as thosedescribed herein. In some embodiments, a TβRII antagonist antibody thatbinds to betaglycan inhibits one or more TGF-beta superfamily ligands,TGFβ superfamily type I receptors, or TGFβ superfamily type II receptorsfrom binding to betaglycan. In some embodiments a TβRII antagonistantibody that binds to betaglycan inhibits one or more TGF-betasuperfamily ligands from binding to betaglycan selected from the groupconsisting of: TGFβ1, TGFβ2, and TGFβ3. In certain aspects, a TβRIIantagonist antibody binds to at least TGFβ1. In some embodiments, aTβRII antagonist antibody that binds to TGFβ1 inhibits TβRII signaling,optionally as measured in a cell-based assay such as those describedherein. In some embodiments, a TβRII antagonist antibody that binds toTGFβ1 inhibits TGFβ1-TβRII, TGFβ1-ALK5, and/or TGFβ1-betaglcyan binding.In certain aspects, a TβRII antagonist antibody binds to at least TGFβ2.In some embodiments, a TβRII antagonist antibody that binds to TGFβ2inhibits TβRII signaling, optionally as measured in a cell-based assaysuch as those described herein. In some embodiments, a TβRII antagonistantibody that binds to TGFβ2 inhibits TGFβ2-TβRII, TGFβ1-ALK5, and/orTGFβ1-betaglcyan binding. In certain embodiments, a TβRII antagonistantibody binds to at least TGFβ3. In some embodiments, a TβRIIantagonist antibody that binds to TGFβ3 inhibits TβRII signaling,optionally as measured in a cell-based assay such as those describedherein. In some embodiments, a TβRII antagonist antibody that binds toTGFβ3 inhibits TGFβ3-TβRII, TGFβ1-ALK5, and/or TGFβ1-betaglcyan binding.In some embodiments, a TβRII antagonist antibody is a multispecificantibody, or a combination of multispecific antibodies, inhibitssignaling in a cell-based assay of one or more of: TGFβ1, TGFβ2, TGFβ3,TβRII, ALK5, and betaglycan. In some embodiments, antibody is a chimericantibody, a humanized antibody, or a human antibody. In someembodiments, the antibody is a single-chain antibody, an F(ab′)2fragment, a single-chain diabody, a tandem single-chain Fv fragment, atandem single-chain diabody, or a fusion protein comprising asingle-chain diabody and at least a portion of an immunoglobulinheavy-chain constant region.

In certain aspects, a TβRII antagonist is a small molecule inhibitor orcombination of small molecule inhibitors. In some embodiments, a TβRIIantagonist small molecule inhibitor is an inhibitor of at least TβRII.In some embodiments, a TβRII antagonist small molecule inhibitor is aninhibitor of at least ALK5. In some embodiments, a TβRII antagonistsmall molecule inhibitor is an inhibitor of at least betaglycan. In someembodiments, a TβRII antagonist small molecule inhibitor is an inhibitorof at least TGFβ1. In some embodiments, a TβRII antagonist smallmolecule inhibitor is an inhibitor of at least TGFβ2. In someembodiments, a TβRII antagonist small molecule inhibitor is an inhibitorof at least TGFβ3.

In certain aspects, a TβRII antagonist is a nucleic acid inhibitor orcombination of nucleic acid inhibitors. In some embodiments, a TβRIIantagonist nucleic acid inhibitor is an inhibitor of at least TβRII. Insome embodiments, a TβRII antagonist nucleic acid inhibitor is aninhibitor of at least ALK5. In some embodiments, a TβRII antagonistnucleic acid inhibitor is an inhibitor of at least betaglycan. In someembodiments, a TβRII antagonist nucleic acid inhibitor is an inhibitorof at least TGFβ1. In some embodiments, a TβRII antagonist nucleic acidinhibitor is an inhibitor of at least TGFβ2. In some embodiments, aTβRII antagonist nucleic acid inhibitor is an inhibitor of at leastTGFβ3.

In certain aspects, the disclosure provides a method of modulating theresponse of a cell to a TGFβ superfamily member, the method comprisingexposing the cell to a TβRII polypeptide or homodimer of the disclosure.

In certain aspects, the disclosure provides a method of modulating theresponse of a cell to a TGFβ superfamily member, the method comprisingexposing the cell to a TβRII polypeptide or homodimer of the disclosure.

In certain aspects, the disclosure relates to use of one or more TβRIIantagonists, optionally in combination of one or more other supportivetherapies or active agents for treating myeloproliferative disorders, inthe manufacture of a medicament for treating, preventing, or reducingthe progression rate and/or severity of a myeloproliferative disorder(e.g., myelofibrosis, polycythemia vera, and essential thrombocytopenia)one or more complications of a myeloproliferative disorder (e.g.,fibrosis, splenomegaly, and inflammation) as described herein. Incertain aspects, the disclosure relates to use of one or more TβRIIantagonists, optionally in combination of one or more other supportivetherapies or active agents for treating a Janus kinase-associateddisorder (e.g., a JAK2 kinase-associated disorder), in the manufactureof a medicament for treating, preventing, or reducing the progressionrate and/or severity of a Janus kinase-associated disorder (e.g.,myelofibrosis, polycythemia vera, and essential thrombocytopenia) one ormore complications of a Janus kinase-associated disorders (e.g.,fibrosis, splenomegaly, and inflammation) as described herein. Incertain aspects, the disclosure relates to one or more TβRIIantagonists, optionally in combination of one or more other supportivetherapies or active agents for treating myeloproliferative disorders,for use in treating, preventing, or reducing the progression rate and/orseverity of a myeloproliferative disorder (e.g., myelofibrosis,polycythemia vera, and essential thrombocytopenia) one or morecomplications of a myeloproliferative disorder (e.g., fibrosis,splenomegaly, and inflammation) as described herein. In certain aspects,the disclosure relates to one or more TβRII antagonists, optionally incombination of one or more other supportive therapies or active agentsfor treating Janus kinase-associated disorders, for use in treating,preventing, or reducing the progression rate and/or severity of a Januskinase-associated disorder (e.g., myelofibrosis, polycythemia vera, andessential thrombocytopenia) one or more complications of a Januskinase-associated disorder (e.g., fibrosis, splenomegaly, andinflammation) as described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

The patent or application file contains at least one drawing executed incolor. Copies of this patent or patent application publication withcolor drawing(s) will be provided by the Office upon request and paymentof the necessary fee.

FIG. 1 shows the amino acid sequence of native precursor for the B(short) isoform of human TGFβ receptor type II (hTβRII) (NP_003233.4).Solid underline indicates the mature extracellular domain (ECD)(residues 23-159), and double underline indicates valine that isreplaced in the A (long) isoform. Dotted underline denotes leader(residues 1-22).

FIG. 2 shows the amino acid sequence of native precursor for the A(long) isoform of human TβRII (NP_001020018.1). Solid underlineindicates the mature ECD (residues 23-184), and double underlineindicates the splice-generated isoleucine substitution. Dotted underlinedenotes leader (residues 1-22).

FIG. 3 shows N-terminal alignment of hTβRII_(short) truncations andtheir hTβRII_(long) counterparts. The 25-amino-acid insertion present inhTβRII_(long) truncations is underlined. Note that the splicing processcauses the valine flanking the insertion site in the short isoform to bereplaced by an isoleucine in the long isoform. Boxed sequence denotesleader.

FIGS. 4A, 4B, and 4C show bone biopsy from vehicle treated JAK2V617Fmice (FIG. 4B), mTβRII-Fc treated JAK2V617F mice (FIG. 4C), and agematched wild-type mice (FIG. 4A). Fibrosis was reduced in bone marrowsamples from mTβRII-Fc treated JAK2V617F mice compared to controlJAK2V617F mice.

FIGS. 5A and 5B show the effect of mTβRII-Fc on red blood cell levels(FIG. 5A) and spleen weight (FIG. 5B) in JAK2V617F mice. mTβRII-Fctreatment had a modest effect on RBC levels and significantly decreasedspleen weight (−29%; p<0.01) compared to vehicle treated mice.

FIGS. 6A and 6B show spleen biopsy from vehicle treated JAK2V617F mice(FIG. 6A) and mTβRII-Fc treated JAK2V617F mice (FIG. 6B). Fibrosis wasreduced in spleen samples from mTβRII-Fc treated JAK2V617F mice comparedto control JAK2V617F mice.

FIGS. 7A and 7B show the effect of mTβRII-Fc and ruxolitinib on redblood cell levels (FIG. 7A) and spleen weight (FIG. 7B) in JAK2V617Fmice. Rux treatment alone or in combination with mTβRII-Fc significantlylowered RBC levels and reduced spleen weights compared to vehicletreated mice (* P<0.05; ** P<0.01; ***P<0.001 vs vehicle). mTβRII-Fctreatment alone had a more modest effect on RBC levels and spleenweights (* P<0.05 and ** P<0.01 vs vehicle).

FIGS. 8A, 8B, 8C, and 8D show bone biopsy from vehicle treated JAK2V617Fmice (FIG. 8A), ruxolitinib treated JAK2V617F mice (FIG. 8B), mTβRII-Fctreated JAK2V617F mice (FIG. 8C), and JAK2V617F mice treated with bothmTβRII-Fc and ruxolitinib (FIG. 8D). Fibrosis was reduced in bone marrowsamples from mTβRII-Fc treated JAK2V617F mice as well as JAK2V617F micetreated with both mTβRII-Fc and ruxolitinib compared to controlJAK2V617F mice.

DETAILED DESCRIPTION OF THE INVENTION 1. Overview

Proteins described herein are the human forms, unless otherwisespecified. NCBI references for the proteins are as follows: human TβRIIisoform A (hTβRII_(long)), NP_001020018.1 and human TβRII isoform B(hTβRII_(short)), NP_003233.4. Sequences of native human TβRII proteinsare set forth in FIGS. 1-2.

The TGFβ superfamily contains a variety of growth factors that sharecommon sequence elements and structural motifs. These proteins are knownto exert biological effects on a large variety of cell types in bothvertebrates and invertebrates. Members of the superfamily performimportant functions during embryonic development in pattern formationand tissue specification and can influence a variety of differentiationprocesses, including adipogenesis, myogenesis, chondrogenesis,cardiogenesis, hematopoiesis, neurogenesis, and epithelial celldifferentiation. By manipulating the activity of a member of the TGFβfamily, it is often possible to cause significant physiological changesin an organism. For example, the Piedmontese and Belgian Blue cattlebreeds carry a loss-of-function mutation in the GDF8 (also calledmyostatin) gene that causes a marked increase in muscle mass [Grobet etal. (1997) Nat Genet 17(1):71-4]. Similarly, in humans, inactive allelesof GDF8 are associated with increased muscle mass and, reportedly,exceptional strength [Schuelke et al. (2004) N Engl J Med 350:2682-8].

TGFβ signals are mediated by heteromeric complexes of type I (e.g. TPRI)and type II (e.g. TβRII) serine/threonine kinase receptors, whichphosphorylate and activate downstream SMAD proteins upon ligandstimulation [Massagué (2000) Nat. Rev. Mol. Cell Biol. 1:169-178]. Thesetype I and type II receptors are transmembrane proteins, composed of aligand-binding extracellular domain with cysteine-rich region, atransmembrane domain, and a cytoplasmic domain with predictedserine/threonine specificity. Type I receptors are essential forsignaling; and type II receptors are required for binding ligands andfor expression of type I receptors. Type I and II receptors form astable complex after ligand binding, resulting in phosphorylation oftype I receptors by type II receptors. TGFβ has three mammalianisoforms, TGFβ1, TGFβ2 and TGFβ3, each with distinct functions in vivo.The binding of TGFβs to TβRII is a crucial step in initiating activationof the TGFβ signaling pathway, leading to phosphorylation of SMAD2, andtranslocation of the activated SMAD2/SMAD4 complex to the nucleus tomodulate gene expression.

TβRII is the known type II receptor for TGFβ and binds with highaffinity to TGFβ1 and TGFβ3. Human TβRII occurs naturally in at leasttwo isoforms A (long) and B (short) generated by alternative splicing inthe extracellular domain (ECD) (FIGS. 2 and 1 and SEQ ID NOS: 6 and 5).The long isoform has a 25-amino-acid insertion and the splicing processcauses the valine flanking the insertion site in the short isoform to bereplaced by an isoleucine in the long isoform. Soluble receptorectodomains can function as scavengers or ligand traps to inhibitligand-receptor interactions. Ligand traps such as soluble TβRII-Fcfusion proteins incorporating the native TβRII extracellular domain(ectodomain) will function as pan-inhibitors against TβRII ligands,including, TGFβ1 and TGFβ3. While in some therapeutic settings thisbroader spectrum of ligand-binding and signal inhibition may beadvantageous, in other settings a more selective molecule may besuperior. It is highly desirable for ligand traps such as TβRIIectodomain polypeptides to exhibit selective ligand-binding profiles.Thus, in certain aspects, the disclosure provides TβRII polypeptides asantagonists of TGFβ1 or TGFβ3 for use in treating various TGFβ1- orTGFβ3-associated disorders. While not wishing to be bound to anyparticular mechanism of action, it is expected that such polypeptidesact by binding to TGFβ1 or TGFβ3 and inhibiting the ability of theseligands to form ternary signaling complexes.

Myeloproliferative disorders are a group of conditions characterized, inpart, by chronic increases in some or all of blood cells (platelets,white blood cells, and red blood cells). This group of blood disordersincludes polycythemia vera (PV), essential thrombocythemia (ET),myelofibrosis (e.g., primary myelofibrosis (PMF), post-polycythemia veramyelofibrosis, and post-essential thrombocythemia myelofibrosis), andchronic myeloid leukemia (CML). It is generally thought thatmyeloproliferative disorders arise from a transformation in ahematopoietic stem cell. Indeed, CML is defined by its causativemolecular lesion, the BCR-ABL fusion, which most commonly results fromthe Philadelphia translocation. Recently, several groups identified again-of-function of tyrosine kinase JAK2 (JAK2V617F) as a majormolecular defect in patients with in the BCR-ABL-negativemyeloproliferative disorders PV, ET, and myelofibrosis (MF). JAK2V617Fmice develop pathology that closely resembles human essentialthrombocythemia and polycythemia vera [Xing et al. (2008) Blood 111:5109-5117]. As they age, these JAK2V617F mice also develop primarymyelofibrosis-like pathology. As disclosed herein, it has beendiscovered that TβRII-Fc treatment can reduce splenomegaly, fibrosis,and other morbidities in a JAK2V617F disease model.

The data presented herein demonstrates that a TβRII antagonist may beused to treat or prevent complications resultant from the JAK2V617Fmutation, which indicates that such therapeutics may be used to treatmyeloproliferative disorders (e.g., polycythemia vera, essentialthrombocythaemia, and myelofibrosis) as well as Janus kinase-associateddisorder (e.g., a JAK2 kinase-associated disorder). In view of theeffects on early stage (e.g., splenomegaly) and reduction/delay of onsetof late stage disease pathology (e.g., fibrosis and pro-inflammatorycytokines), TβRII antagonists may be particular well suited fortreatment of polycythemia vera and essential thrombocythaemia toprevent/delay the onset or reduce the severity of fibrosis and otherlate stage disease complications and thus prevent/delay the transitioninto secondary myelofibrosis disease (post-polycythemia veramyelofibrosis and post-essential thrombocythaemia myelofibrosis,respectively). Also, TβRII antagonists clearly demonstrate positiveeffects in treated last stage fibrosis and inflammation in myelofibrosispatients.

The terms used in this specification generally have their ordinarymeanings in the art, within the context of this invention and in thespecific context where each term is used. Certain terms are discussedbelow or elsewhere in the specification, to provide additional guidanceto the practitioner in describing the compositions and methods of theinvention and how to make and use them. The scope or meaning of any useof a term will be apparent from the specific context in which the termis used.

“Homologous,” in all its grammatical forms and spelling variations,refers to the relationship between two proteins that possess a “commonevolutionary origin,” including proteins from superfamilies in the samespecies of organism, as well as homologous proteins from differentspecies of organism. Such proteins (and their encoding nucleic acids)have sequence homology, as reflected by their sequence similarity,whether in terms of percent identity or by the presence of specificresidues or motifs and conserved positions. The term “sequencesimilarity,” in all its grammatical forms, refers to the degree ofidentity or correspondence between nucleic acid or amino acid sequencesthat may or may not share a common evolutionary origin. However, incommon usage and in the instant application, the term “homologous,” whenmodified with an adverb such as “highly,” may refer to sequencesimilarity and may or may not relate to a common evolutionary origin.

“Percent (%) sequence identity” with respect to a reference polypeptide(or nucleotide) sequence is defined as the percentage of amino acidresidues (or nucleic acids) in a candidate sequence that are identicalto the amino acid residues (or nucleic acids) in the referencepolypeptide (nucleotide) sequence, after aligning the sequences andintroducing gaps, if necessary, to achieve the maximum percent sequenceidentity, and not considering any conservative substitutions as part ofthe sequence identity. Alignment for purposes of determining percentamino acid sequence identity can be achieved in various ways that arewithin the skill in the art, for instance, using publicly availablecomputer software such as BLAST, BLAST-2, ALIGN or Megalign (DNASTAR)software. Those skilled in the art can determine appropriate parametersfor aligning sequences, including any algorithms needed to achievemaximal alignment over the full length of the sequences being compared.For purposes herein, however, % amino acid (nucleic acid) sequenceidentity values are generated using the sequence comparison computerprogram ALIGN-2. The ALIGN-2 sequence comparison computer program wasauthored by Genentech, Inc., and the source code has been filed withuser documentation in the U.S. Copyright Office, Washington D.C., 20559,where it is registered under U.S. Copyright Registration No. TXU510087.The ALIGN-2 program is publicly available from Genentech, Inc., SouthSan Francisco, Calif., or may be compiled from the source code. TheALIGN-2 program should be compiled for use on a UNIX operating system,including digital UNIX V4.0D. All sequence comparison parameters are setby the ALIGN-2 program and do not vary.

“Agonize”, in all its grammatical forms, refers to the process ofactivating a protein and/or gene (e.g., by activating or amplifying thatprotein's gene expression or by inducing an inactive protein to enter anactive state) or increasing a protein's and/or gene's activity.

“Antagonize”, in all its grammatical forms, refers to the process ofinhibiting a protein and/or gene (e.g., by inhibiting or decreasing thatprotein's gene expression or by inducing an active protein to enter aninactive state) or decreasing a protein's and/or gene's activity.

The terms “about” and “approximately” as used in connection with anumerical value throughout the specification and the claims denotes aninterval of accuracy, familiar and acceptable to a person skilled in theart. In general, such interval of accuracy is ±10%. Alternatively, andparticularly in biological systems, the terms “about” and“approximately” may mean values that are within an order of magnitude,preferably <5-fold and more preferably <2-fold of a given value.

Numeric ranges disclosed herein are inclusive of the numbers definingthe ranges.

The terms “a” and “an” include plural referents unless the context inwhich the term is used clearly dictates otherwise. The terms “a” (or“an”), as well as the terms “one or more,” and “at least one” can beused interchangeably herein. Furthermore, “and/or” where used herein isto be taken as specific disclosure of each of the two or more specifiedfeatures or components with or without the other. Thus, the term“and/or” as used in a phrase such as “A and/or B” herein is intended toinclude “A and B,” “A or B,” “A” (alone), and “B” (alone). Likewise, theterm “and/or” as used in a phrase such as “A, B, and/or C” is intendedto encompass each of the following aspects: A, B, and C; A, B, or C; Aor C; A or B; B or C; A and C; A and B; B and C; A (alone); B (alone);and C (alone).

Throughout this specification, the word “comprise” or variations such as“comprises” or “comprising” will be understood to imply the inclusion ofa stated integer or groups of integers but not the exclusion of anyother integer or group of integers.

2. TβRII Antagonists

In part, the data presented herein demonstrates that a TβRII antagonist(inhibitor) can be used to treat a myeloproliferative disorder (e.g.,polycythemia vera, essential thrombocythemia, and myelofibrosis) and/ora patient with a Janus kinase-associated disorder (e.g., a JAK2kinase-associated disorder). In particular, a TβRII polypeptide wasshown to be effective in improving various myeloproliferative diseasecomplications including, for example, splenomegaly, high inflammatorycytokine levels, and fibrosis. Accordingly, the disclosure provides, inpart, various TβRII antagonists that can be used, alone or incombination with one or more additional active agents and/or supportivetherapies, to treat, prevent, reduce the progression rate and/orseverity of a myeloproliferative disorder and/or a patient with a Januskinase-associated disorder or one or more complications of amyeloproliferative disorder and/or a Janus kinase-associated disorder.Although TβRII polypeptides may affect myeloproliferative disease and/ora patient with a Janus kinase-associated disorder through a mechanismother than inhibition of TβRII ligands [e.g., inhibition of one or moreof TGFβ1, TGFβ2, and/or TGFβ3 may be an indicator of the tendency of anagent to inhibit the activities of a spectrum of additional agents,including, perhaps, other members of the TGF-beta superfamily and suchcollective inhibition may lead to the desired effect on, for example, amyeloproliferative disease and/or a Janus kinase-associated disorder],other types of TGFβ antagonists [e.g., antagonists of the TβRIIreceptor, antagonists of one or more TβRII ligands (e.g., TGFβ1, TGFβ2,and TGFβ3), antagonists of one or more TβRII-associated type I receptors(e.g., ALK5), antagonists of one or more TβRII-associated co-receptor(e.g., betaglycan), antagonists or one or more TβRII downstreamsignaling components (Smads), or combinations of such antagonists] willbe useful in the treatment of myeloproliferative disorders and/or Januskinase-associated disorders, particularly in the treatment, prevention,or reduction in progression rate and/or severity of one or morecomplications of a myeloproliferative disorder and/or a Januskinase-associated disorder. Such antagonists include, for example, forexample, TβRII polypeptides and variants thereof, anti-TGFβ antibodies,anti-ALK5 antibodies, anti-betaglycan antibodies, and anti-TβRIIantibodies; nucleic acids that inhibit the activity or expression (e.g.,transcription, translation, secretion from a cell, or combinationsthereof) of one or more of TGFβ1, TGFβ2, TGFβ3, ALK5, betaglycan, andTβRII; as well as small molecules that inhibit the activity orexpression (e.g., transcription, translation, secretion from a cell, orcombinations thereof) of one or more of TGFβ1, TGFβ2, TGFβ3, ALK5,betaglycan and TβRII.

A. TβRII Polypeptides

In certain aspects, a TβRII antagonist to be used in accordance with themethods and uses disclosed herein is a TβRII polypeptide or variantthereof (TβRII antagonist polypeptide). A TβRII polypeptide, orcombination of polypeptides, may inhibit, for example, one or more TβRIIligands (e.g., TGFβ1, TGFβ2, and TGFβ3), TβRII receptor,TβRII-associated type I receptor (e.g., ALK5), and/or TβRII-associatedco-receptor (e.g., betaglycan). In some embodiments, the ability for aTβRII polypeptide, or combination of polypeptides, to inhibit signaling(e.g., Smad signaling) is determined in a cell-based assay including,for example, those described herein. A TβRII polypeptide, or combinationof polypeptides, may be used alone or in combination with one or moreadditional supportive therapies or active agents to treat, prevent, orreduce the progression rate and/or severity of a myeloproliferativedisorder (e.g., myelofibrosis, polycythemia vera, and essentialthrombocythaemia) and/or a Janus kinase-associated disorder or one ormore complications of a myeloproliferative disorder and/or a Januskinase-associated disorder (e.g., a JAK2 kinase-associated disorder).

Naturally occurring TβRII proteins are transmembrane proteins, with aportion of the protein positioned outside the cell (the extracellularportion) and a portion of the protein positioned inside the cell (theintracellular portion). Aspects of the present disclosure encompassvariant TβRII polypeptides comprising mutations within the extracellulardomain and/or truncated portions of the extracellular domain of TβRII.As described above, human TβRII occurs naturally in at least twoisoforms—A (long) and B (short)—generated by alternative splicing in theextracellular domain (ECD) (FIGS. 2 and 1 and SEQ ID NOS: 6 and 5). SEQID NO: 7, which corresponds to residues 23-159 of SEQ ID NO: 5, depictsthe native full-length extracellular domain of the short isoform ofTβRII. SEQ ID NO: 13, which corresponds to residues 23-184 of SEQ ID NO:6, depicts the native full-length extracellular domain of the longisoform of TβRII. Unless noted otherwise, amino acid position numberingwith regard to variants based on the TβRII short and long isoformsrefers to the corresponding position in the native precursors, SEQ IDNO: 5 and SEQ ID NO:6, respectively.

In certain embodiments, the disclosure provides variant TβRIIpolypeptides. A TβRII polypeptide of the disclosure may bind to andinhibit the function of a TGFβ superfamily member, such as but notlimited to, TGFβ1 or TGFβ3. TβRII polypeptides may include a polypeptideconsisting of, or comprising, an amino acid sequence at least 80%identical, and optionally at least 85%, 90%, 91%, 92%, 93%, 94% 95%,96%, 97%, 98%, 99%, or 100% identical to a truncated ECD domain of anaturally occurring TβRII polypeptide, whose C-terminus occurs at any ofamino acids 153-159 (e.g., 153, 154, 155, 156, 157, 158, or 159) of SEQID NO: 5. TβRII polypeptides may include a polypeptide consisting of, orcomprising, an amino acid sequence at least 80% identical, andoptionally at least 85%, 90%, 91%, 92%, 93%, 94% 95%, 96%, 97%, 98%,99%, or 100% identical to a truncated ECD domain of a naturallyoccurring TβRII polypeptide, whose C-terminus occurs at any of aminoacids 178-184 (e.g., 178, 179, 180, 181, 182, 183, or 184) of SEQ ID NO:6. Optionally, a TβRII polypeptide does not include more than 5consecutive amino acids, or more than 10, 20, 30, 40, 50, 52, 60, 70,80, 90, 100, 150 or 200 or more consecutive amino acids from a sequenceconsisting of amino acids 160-567 of SEQ ID NO: 5 or from a sequenceconsisting of amino acids 185-592 of SEQ ID NO: 6. The unprocessed TβRIIpolypeptide may either include or exclude any signal sequence, as wellas any sequence N-terminal to the signal sequence. As elaborated herein,the N-terminus of the mature (processed) TβRII polypeptide may occur atany of amino acids 23-35 of SEQ ID NO: 5 or 23-60 of SEQ ID NO: 6.Examples of mature TβRII polypeptides include, but are not limited to,amino acids 23-159 of SEQ ID NO: 5 (set forth in SEQ ID NO: 7), aminoacids 29-159 of SEQ ID NO: 5 (set forth in SEQ ID NO: 105), amino acids35-159 of SEQ ID NO: 5 (set forth in SEQ ID NO: 10), amino acids 23-153of SEQ ID NO: 5 (set forth in SEQ ID NO: 11), amino acids 29-153 of SEQID NO: 5 (set forth in SEQ ID NO: 48), amino acids 35-153 of SEQ ID NO:5 (set forth in SEQ ID NO: 47), amino acids 23-184 of SEQ ID NO: 6 (setforth in SEQ ID NO: 13), amino acids 29-184 of SEQ ID NO: 6 (set forthin SEQ ID NO: 15), amino acids 35-184 of SEQ ID NO:6 (set forth in SEQID NO: 10), amino acids 23-178 of SEQ ID NO: 6 (set forth in SEQ ID NO:16), amino acids 29-178 of SEQ ID NO: 6 (set forth in SEQ ID NO: 49),and amino acids 35-178 of SEQ ID NO: 6 (set forth in SEQ ID NO: 47).Likewise, a TβRII polypeptide may comprise a polypeptide that is encodedby nucleotides 73-465 of SEQ ID NO: 30, nucleotides 73-447 of SEQ ID NO:34, nucleotides 73-465 of SEQ ID NO: 38, nucleotides 91-465 of SEQ IDNO: 38, or nucleotides 109-465 of SEQ ID NO: 38, or silent variantsthereof or nucleic acids that hybridize to the complement thereof understringent hybridization conditions (generally, such conditions are knownin the art but may, for example, involve hybridization in 50% v/vformamide, 5×SSC, 2% w/v blocking agent, 0.1% N-lauroylsarcosine, and0.3% SDS at 65° C. overnight and washing in, for example, 5×SSC at about65° C.). It will be understood by one of skill in the art thatcorresponding variants based on the long isoform of TβRII will includenucleotide sequences encoding the 25-amino acid insertion along with aconservative Val-Ile substitution at the flanking position C-terminal tothe insertion. The TβRII polypeptides accordingly may include isolatedextracellular portions of TβRII polypeptides, including both the shortand the long isoforms, variants thereof (including variants thatcomprise, for example, no more than 2, 3, 4, 5, 10, 15, 20, 25, 30, or35 amino acid substitutions in the sequence corresponding to amino acids23-159 of SEQ ID NO: 5 or amino acids 23-184 of SEQ ID NO: 6), fragmentsthereof, and fusion proteins comprising any of the foregoing, but ineach case preferably any of the foregoing TβRII polypeptides will retainsubstantial affinity for at least one of TGFβ1 or TGFβ3. Generally, aTβRII polypeptide will be designed to be soluble in aqueous solutions atbiologically relevant temperatures, pH levels, and osmolarity.

In some embodiments, the variant TβRII polypeptides of the disclosurecomprise one or more mutations in the extracellular domain that conferan altered ligand binding profile. A TβRII polypeptide may include one,two, five or more alterations in the amino acid sequence relative to thecorresponding portion of a naturally occurring TβRII polypeptide. Insome embodiments, the mutation results in a substitution, insertion, ordeletion at the position corresponding to position 70 of SEQ ID NO: 5.In some embodiments, the mutation results in a substitution, insertion,or deletion at the position corresponding to position 110 of SEQ ID NO:5. Examples include, but are not limited to, an N to D substitution or aD to K substitution in the positions corresponding to positions 70 and110, respectively, of SEQ ID NO: 5. Examples of such variant TβRIIpolypeptides include, but are not limited to, the sequences set forth inSEQ ID NO: 8, SEQ ID NO:14, SEQ ID NO: 12 and SEQ ID NO: 17. A TβRIIpolypeptide may comprise a polypeptide or portion thereof that isencoded by nucleotides 73-483 of SEQ ID NO: 26, nucleotides 73-465 ofSEQ ID NO: 42 or silent variants thereof or nucleic acids that hybridizeto the complement thereof under stringent hybridization conditions.

In some embodiments, the variant TβRII polypeptides of the disclosurefurther comprise an insertion of 36 amino acids (SEQ ID NO: 18) betweenthe pair of glutamate residues (positions 151 and 152 of SEQ ID NO: 5,or positions 176 and 177 of SEQ ID NO: 6) located near the C-terminus ofthe human TβRII ECD, as occurs naturally in the human TβRII isoform C(Konrad et al., BMC Genomics 8:318, 2007).

The disclosure further demonstrates that TβRII polypeptides can bemodified to selectively antagonize TβRII ligands. Data presented hereshow that Fc fusion proteins comprising shorter N-terminally andC-terminally truncated variants of TβRII polypeptides displaydifferential inhibitory effects on cellular signaling mediated by TGFβ1and TGFβ3. Specifically, N-terminally truncated variants beginning atamino acids 29 or 35 of SEQ ID NO: 5 and carrying, respectively, a 6- or12-amino acid N-terminal truncation of the extracellular domain, werefound to significantly reduced potency for inhibiting TGFβ3 whilemaintaining an intermediate degree of TGFβ1 inhibition, compared to thefull length extracellular domain of the short isoform of TβRII.C-terminally truncated variants, ending at amino acid 153 of SEQ ID NO:5 and carrying a 6-amino acid C-terminal truncation of the extracellulardomain had no substantial effect on ligand binding and may therefore beused interchangeably with full length versions. An N to D substitutionat the position corresponding to position 70 of SEQ ID NO: 5, was foundto inhibit TGFβ3 potently and negligible effect on TGFβ1. The N70residue represents a potential glycosylation site. Further, an Fc fusionprotein comprising a D to K substitution at the position correspondingto position 110 of SEQ ID NO: 5, was found to significantly reducedpotency for inhibiting TGFβ1 while maintaining an intermediate degree ofTGFβ3 inhibition compared to the full length extracellular domain of theshort isoform of TβRII. The region around position 110 has not beenassociated with selectivity for the known TβRII ligands TGFβ1, TGFβ2 andTGFβ3. Thus, unexpectedly, TβRII polypeptides that contain mutations inthe ECD, such as but not limited to, N70D and D110K (the numbering ofthe residues corresponds to that of SEQ ID NO: 5) and/or begin betweenamino acids 29 and 35 and/or terminate between amino acid 153 and aminoacid 159 are all expected to be active and exhibit widely differentinhibitory potencies towards the different ligands. Any of thesetruncated variant forms may be desirable to use, depending on theclinical or experimental setting.

In certain embodiments, a TβRII polypeptide binds to TGFβ1, and theTβRII polypeptide does not show substantial binding to TGFβ3. In certainembodiments, a TβRII polypeptide binds to TGFβ3, and the TβRIIpolypeptide does not show substantial binding to TGFβ1. Binding may beassessed, e.g., using purified proteins in solution or in a surfaceplasmon resonance system, such as a Biacore™ system.

In certain embodiments, a TβRII polypeptide inhibits TGFβ1 cellularsignaling, and the TβRII polypeptide has an intermediate or limitedinhibitory effect on TGFβ3. In certain embodiments, a TβRII polypeptideinhibits TGFβ3 cellular signaling, and the TβRII polypeptide has anintermediate or limited inhibitory effect on TGFβ1. Inhibitory effect oncell signaling can be assayed by methods known in the art.

Taken together, an active portion of a TβRII polypeptide may compriseamino acid sequences 23-153, 23-154, 23-155, 23-156, 23-157, or 23-158of SEQ ID NO: 5, as well as variants of these sequences starting at anyof amino acids 24-35 of SEQ ID NO: 5. Similarly, an active portion of aTβRII polypeptide may comprise amino acid sequences 23-178, 23-179,23-180, 23-181, 23-182, or 23-183 of SEQ ID NO: 6, as well as variantsof these sequences starting at any of amino acids 24-60 of SEQ ID NO: 6.Exemplary TβRII polypeptides comprise amino acid sequences 29-159,35-159, 23-153, 29-153 and 35-153 of SEQ ID NO: 5 or amino acidsequences 29-184, 60-184, 23-178, 29-178 and 60-178 of SEQ ID NO: 6.Variants within these ranges are also contemplated, particularly thosehaving at least 85%, 90%, 91%, 92%, 93%, 94% 95%, 96%, 97%, 98%, 99%, or100% identity to the corresponding portion of SEQ ID NO: 5 or SEQ ID NO:6. A TβRII polypeptide may be selected that does not include thesequence consisting of amino acids 160-567 of SEQ ID NO:5 or amino acids185-592 of SEQ ID NO:6.

As described above, the disclosure provides TβRII polypeptides sharing aspecified degree of sequence identity or similarity to a naturallyoccurring TβRII polypeptide. To determine the percent identity of twoamino acid sequences, the sequences are aligned for optimal comparisonpurposes (e.g., gaps can be introduced in one or both of a first and asecond amino acid or nucleic acid sequence for optimal alignment andnon-homologous sequences can be disregarded for comparison purposes).The amino acid residues at corresponding amino acid positions are thencompared. When a position in the first sequence is occupied by the sameamino acid residue as the corresponding position in the second sequence,then the molecules are identical at that position (as used herein aminoacid “identity” is equivalent to amino acid “homology”). The percentidentity between the two sequences is a function of the number ofidentical positions shared by the sequences, taking into account thenumber of gaps, and the length of each gap, which need to be introducedfor optimal alignment of the two sequences.

The comparison of sequences and determination of percent identity andsimilarity between two sequences can be accomplished using amathematical algorithm (Computational Molecular Biology, Lesk, A. M.,ed., Oxford University Press, New York, 1988; Biocomputing: Informaticsand Genome Projects, Smith, D. W., ed., Academic Press, New York, 1993;Computer Analysis of Sequence Data, Part 1, Griffin, A. M., and Griffin,H. G., eds., Humana Press, New Jersey, 1994; Sequence Analysis inMolecular Biology, von Heinje, G., Academic Press, 1987; and SequenceAnalysis Primer, Gribskov, M. and Devereux, J., eds., M Stockton Press,New York, 1991).

In one embodiment, the percent identity between two amino acid sequencesis determined using the Needleman and Wunsch (J Mol. Biol. (48):444-453(1970)) algorithm which has been incorporated into the GAP program inthe GCG software package (available at http://www.gcg.com). In aspecific embodiment, the following parameters are used in the GAPprogram: either a Blosum 62 matrix or a PAM250 matrix, and a gap weightof 16, 14, 12, 10, 8, 6, or 4 and a length weight of 1, 2, 3, 4, 5, or6. In yet another embodiment, the percent identity between twonucleotide sequences is determined using the GAP program in the GCGsoftware package (Devereux, J., et al., Nucleic Acids Res. 12(1):387(1984)) (available at http://www.gcg.com). Exemplary parameters includeusing a NWSgapdna.CMP matrix and a gap weight of 40, 50, 60, 70, or 80and a length weight of 1, 2, 3, 4, 5, or 6. Unless otherwise specified,percent identity between two amino acid sequences is to be determinedusing the GAP program using a Blosum 62 matrix, a GAP weight of 10 and alength weight of 3, and if such algorithm cannot compute the desiredpercent identity, a suitable alternative disclosed herein should beselected.

In another embodiment, the percent identity between two amino acidsequences is determined using the algorithm of E. Myers and W. Miller(CABIOS, 4:11-17 (1989)) which has been incorporated into the ALIGNprogram (version 2.0), using a PAM120 weight residue table, a gap lengthpenalty of 12 and a gap penalty of 4.

Another embodiment for determining the best overall alignment betweentwo amino acid sequences can be determined using the FASTDB computerprogram based on the algorithm of Brutlag et al. (Comp. App. Biosci.,6:237-245 (1990)). In a sequence alignment the query and subjectsequences are both amino acid sequences. The result of said globalsequence alignment is presented in terms of percent identity. In oneembodiment, amino acid sequence identity is performed using the FASTDBcomputer program based on the algorithm of Brutlag et al. (Comp. App.Biosci., 6:237-245 (1990)). In a specific embodiment, parametersemployed to calculate percent identity and similarity of an amino acidalignment comprise: Matrix=PAM 150, k-tuple=2, Mismatch Penalty=1,Joining Penalty=20, Randomization Group Length=0, Cutoff Score=1, GapPenalty=5 and Gap Size Penalty=0.05.

TβRII polypeptides may additionally include any of various leadersequences at the N-terminus. Such a sequence would allow the peptides tobe expressed and targeted to the secretion pathway in a eukaryoticsystem. See, e.g., Ernst et al., U.S. Pat. No. 5,082,783 (1992).Alternatively, a native TβRII signal sequence may be used to effectextrusion from the cell. Possible leader sequences include nativeleaders, tissue plasminogen activator (TPA) and honeybee mellitin (SEQID NOs. 22-24, respectively). Examples of TβRII-Fc fusion proteinsincorporating a TPA leader sequence include SEQ ID NOs: 25, 27, 29, 31,33, 35, 37, 39, 41, 43, 101 and 103. Processing of signal peptides mayvary depending on the leader sequence chosen, the cell type used andculture conditions, among other variables, and therefore actualN-terminal start sites for mature TβRII polypeptides may shift by 1, 2,3, 4 or 5 amino acids in either the N-terminal or C-terminal direction.Examples of TβRII-Fc fusion proteins include SEQ ID NOs: 25, 27, 29, 31,33, 35, 37, 39, 41, 43, 50, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 101,and 103, as shown herein with the TβRII polypeptide portion underlined(see Examples). It will be understood by one of skill in the art thatcorresponding variants based on the long isoform of TβRII will includethe 25-amino acid insertion along with a conservative Val-Ilesubstitution at the flanking position C-terminal to the insertion. Incertain aspects the disclosure relates to a TβRII polypeptide thatcomprises amino acid sequence that is at least 80%, 85%, 90%, 91%, 92%,93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acidsequence of SEQ ID NO: 101 as well as uses thereof in accordance withthe methods described herein. In certain aspects the disclosure relatesto a TβRII polypeptide that comprises an amino acid sequence that is atleast 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or100% identical to the amino acid sequence of SEQ ID NO: 103 as well asuses thereof in accordance with the methods described herein. In certainaspects the disclosure relates to a TβRII polypeptide that comprisesamino acid sequence that is at least 80%, 85%, 90%, 91%, 92%, 93%, 94%,95%, 96%, 97%, 98%, 99%, or 100% identical to an amino acid sequencethat begins at any one of amino acids 25-46 (e.g., 25, 26, 27, 28, 29,30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, or 46)of SEQ ID NO: 101 and ends and any one of amino acids 170-186 (e.g.,170, 171, 172, 173, 174, 175, 176, 177, 178, 179, 180, 181, 182, 183,184, 185, or 186) of SEQ ID NO: 101 as well as uses thereof inaccordance with the methods described herein.

In certain embodiments, the present disclosure contemplates specificmutations of the TβRII polypeptides so as to alter the glycosylation ofthe polypeptide. Such mutations may be selected so as to introduce oreliminate one or more glycosylation sites, such as O-linked or N-linkedglycosylation sites. Asparagine-linked glycosylation recognition sitesgenerally comprise a tripeptide sequence, asparagine-X-threonine (orasparagine-X-serine) (where “X” is any amino acid) which is specificallyrecognized by appropriate cellular glycosylation enzymes. The alterationmay also be made by the addition of, or substitution by, one or moreserine or threonine residues to the sequence of the wild-type TβRIIpolypeptide (for O-linked glycosylation sites). A variety of amino acidsubstitutions or deletions at one or both of the first or third aminoacid positions of a glycosylation recognition site (and/or amino aciddeletion at the second position) results in non-glycosylation at themodified tripeptide sequence. Another means of increasing the number ofcarbohydrate moieties on a TβRII polypeptide is by chemical or enzymaticcoupling of glycosides to the TβRII polypeptide. Depending on thecoupling mode used, the sugar(s) may be attached to (a) arginine andhistidine; (b) free carboxyl groups; (c) free sulfhydryl groups such asthose of cysteine; (d) free hydroxyl groups such as those of serine,threonine, or hydroxyproline; (e) aromatic residues such as those ofphenylalanine, tyrosine, or tryptophan; or (f) the amide group ofglutamine. These methods are described in WO 87/05330 published Sep. 11,1987, and in Aplin and Wriston (1981) CRC Crit. Rev. Biochem., pp.259-306, incorporated by reference herein. Removal of one or morecarbohydrate moieties present on a TβRII polypeptide may be accomplishedchemically and/or enzymatically. Chemical deglycosylation may involve,for example, exposure of the TβRII polypeptide to the compoundtrifluoromethanesulfonic acid, or an equivalent compound. This treatmentresults in the cleavage of most or all sugars except the linking sugar(N-acetylglucosamine or N-acetylgalactosamine), while leaving the aminoacid sequence intact. Chemical deglycosylation is further described byHakimuddin et al. (1987) Arch. Biochem. Biophys. 259:52 and by Edge etal. (1981) Anal. Biochem. 118:131. Enzymatic cleavage of carbohydratemoieties on TβRII polypeptides can be achieved by the use of a varietyof endo- and exo-glycosidases as described by Thotakura et al. (1987)Meth. Enzymol. 138:350. The sequence of a TβRII polypeptide may beadjusted, as appropriate, depending on the type of expression systemused, as mammalian, yeast, insect and plant cells may all introducediffering glycosylation patterns that can be affected by the amino acidsequence of the peptide. In general, TβRII polypeptides for use inhumans will be expressed in a mammalian cell line that provides properglycosylation, such as HEK293 or CHO cell lines, although othermammalian expression cell lines, yeast cell lines with engineeredglycosylation enzymes, and insect cells are expected to be useful aswell.

This disclosure further contemplates a method of generating mutants,particularly sets of combinatorial mutants of a TβRII polypeptide, aswell as truncation mutants; pools of combinatorial mutants areespecially useful for identifying functional variant sequences. Thepurpose of screening such combinatorial libraries may be to generate,for example, TβRII polypeptide variants which can act as either agonistsor antagonist, or alternatively, which possess novel activities alltogether. A variety of screening assays are provided below, and suchassays may be used to evaluate variants. For example, a TβRIIpolypeptide variant may be screened for ability to bind to a TβRIIligand, to prevent binding of a TβRII ligand to a TβRII polypeptide orto interfere with signaling caused by a TβRII ligand. The activity of aTβRII polypeptide or its variants may also be tested in a cell-based orin vivo assay, particularly any of the assays disclosed in the Examples.

Combinatorially-derived variants can be generated which have a selectiveor generally increased potency relative to a TβRII polypeptidecomprising an extracellular domain of a naturally occurring TβRIIpolypeptide. Likewise, mutagenesis can give rise to variants which haveserum half-lives dramatically different than the corresponding wild-typeTβRII polypeptide. For example, the altered protein can be renderedeither more stable or less stable to proteolytic degradation or otherprocesses which result in destruction of, or otherwise elimination orinactivation of, a native TβRII polypeptide. Such variants, and thegenes which encode them, can be utilized to alter TβRII polypeptidelevels by modulating the half-life of the TβRII polypeptides. Forinstance, a short half-life can give rise to more transient biologicaleffects and can allow tighter control of recombinant TβRII polypeptidelevels within the patient. In an Fc fusion protein, mutations may bemade in the linker (if any) and/or the Fc portion to alter the half-lifeof the protein.

A combinatorial library may be produced by way of a degenerate libraryof genes encoding a library of polypeptides which each include at leasta portion of potential TβRII polypeptide sequences. For instance, amixture of synthetic oligonucleotides can be enzymatically ligated intogene sequences such that the degenerate set of potential TβRIIpolypeptide nucleotide sequences are expressible as individualpolypeptides, or alternatively, as a set of larger fusion proteins(e.g., for phage display).

There are many ways by which the library of potential TβRII polypeptidevariants can be generated from a degenerate oligonucleotide sequence.Chemical synthesis of a degenerate gene sequence can be carried out inan automatic DNA synthesizer, and the synthetic genes then be ligatedinto an appropriate vector for expression. The synthesis of degenerateoligonucleotides is well known in the art (see for example, Narang, S A(1983) Tetrahedron 39:3; Itakura et al., (1981) Recombinant DNA, Proc.3rd Cleveland Sympos. Macromolecules, ed. AG Walton, Amsterdam: Elsevierpp273-289; Itakura et al., (1984) Annu. Rev. Biochem. 53:323; Itakura etal., (1984) Science 198:1056; Ike et al., (1983) Nucleic Acid Res.11:477). Such techniques have been employed in the directed evolution ofother proteins (see, for example, Scott et al., (1990) Science249:386-390; Roberts et al., (1992) PNAS USA 89:2429-2433; Devlin etal., (1990) Science 249: 404-406; Cwirla et al., (1990) PNAS USA 87:6378-6382; as well as U.S. Pat. Nos. 5,223,409, 5,198,346, and5,096,815).

Alternatively, other forms of mutagenesis can be utilized to generate acombinatorial library. For example, TβRII polypeptide variants can begenerated and isolated from a library by screening using, for example,alanine scanning mutagenesis and the like (Ruf et al., (1994)Biochemistry 33:1565-1572; Wang et al., (1994) J. Biol. Chem.269:3095-3099; Balint et al., (1993) Gene 137:109-118; Grodberg et al.,(1993) Eur. J. Biochem. 218:597-601; Nagashima et al., (1993) J. Biol.Chem. 268:2888-2892; Lowman et al., (1991) Biochemistry 30:10832-10838;and Cunningham et al., (1989) Science 244:1081-1085), by linker scanningmutagenesis (Gustin et al., (1993) Virology 193:653-660; Brown et al.,(1992) Mol. Cell Biol. 12:2644-2652; McKnight et al., (1982) Science232:316); by saturation mutagenesis (Meyers et al., (1986) Science232:613); by PCR mutagenesis (Leung et al., (1989) Method Cell Mol Biol1:11-19); or by random mutagenesis, including chemical mutagenesis, etc.(Miller et al., (1992) A Short Course in Bacterial Genetics, CSHL Press,Cold Spring Harbor, N.Y.; and Greener et al., (1994) Strategies in MolBiol 7:32-34). Linker scanning mutagenesis, particularly in acombinatorial setting, is an attractive method for identifying truncated(bioactive) forms of TβRII polypeptides.

A wide range of techniques are known in the art for screening geneproducts of combinatorial libraries made by point mutations andtruncations, and, for that matter, for screening cDNA libraries for geneproducts having a certain property. Such techniques will be generallyadaptable for rapid screening of the gene libraries generated by thecombinatorial mutagenesis of TβRII polypeptides. The most widely usedtechniques for screening large gene libraries typically comprisescloning the gene library into replicable expression vectors,transforming appropriate cells with the resulting library of vectors,and expressing the combinatorial genes under conditions in whichdetection of a desired activity facilitates relatively easy isolation ofthe vector encoding the gene whose product was detected. Preferredassays include TβRII ligand binding assays and ligand-mediated cellsignaling assays.

In certain embodiments, the TβRII polypeptides of the disclosure mayfurther comprise post-translational modifications in addition to anythat are naturally present in the TβRII polypeptides. Such modificationsinclude, but are not limited to, acetylation, carboxylation,glycosylation, phosphorylation, lipidation, pegylation (polyethyleneglycol) and acylation. As a result, the modified TβRII polypeptides maycontain non-amino acid elements, such as polyethylene glycols, lipids,mono- or poly-saccharides, and phosphates. Effects of such non-aminoacid elements on the functionality of a TβRII polypeptide may be testedas described herein for other TβRII polypeptide variants. When a TβRIIpolypeptide is produced in cells by cleaving a nascent form of the TβRIIpolypeptide, post-translational processing may also be important forcorrect folding and/or function of the protein. Different cells (such asCHO, HeLa, MDCK, 293, WI38, NIH-3T3 or HEK-293) have specific cellularmachinery and characteristic mechanisms for such post-translationalactivities and may be chosen to ensure the correct modification andprocessing of the TβRII polypeptides.

In certain aspects, functional variants or modified forms of the TβRIIpolypeptides include fusion proteins having at least a portion of theTβRII polypeptides and one or more fusion domains. Well-known examplesof such fusion domains include, but are not limited to, polyhistidine,Glu-Glu, glutathione S transferase (GST), thioredoxin, protein A,protein G, an immunoglobulin heavy chain constant region (Fc), maltosebinding protein (MBP), or human serum albumin. A fusion domain may beselected so as to confer a desired property. For example, some fusiondomains are particularly useful for isolation of the fusion proteins byaffinity chromatography. For the purpose of affinity purification,relevant matrices for affinity chromatography, such as glutathione-,amylase-, and nickel- or cobalt-conjugated resins are used. Many of suchmatrices are available in “kit” form, such as the Pharmacia GSTpurification system and the QIAexpress™ system (Qiagen) useful with(HIS₆) fusion partners. As another example, a fusion domain may beselected so as to facilitate detection of the TβRII polypeptides.Examples of such detection domains include the various fluorescentproteins (e.g., GFP) as well as “epitope tags,” which are usually shortpeptide sequences for which a specific antibody is available. Well knownepitope tags for which specific monoclonal antibodies are readilyavailable include FLAG, influenza virus haemagglutinin (HA), and c-myctags. In some cases, the fusion domains have a protease cleavage site,such as for Factor Xa or Thrombin, which allows the relevant protease topartially digest the fusion proteins and thereby liberate therecombinant proteins therefrom. The liberated proteins can then beisolated from the fusion domain by subsequent chromatographicseparation. In certain preferred embodiments, a TβRII polypeptide isfused with a domain that stabilizes the TβRII polypeptide in vivo (a“stabilizer” domain). By “stabilizing” is meant anything that increasesserum half-life, regardless of whether this is because of decreaseddestruction, decreased clearance by the kidney, or other pharmacokineticeffect. Fusions with the Fc portion of an immunoglobulin are known toconfer desirable pharmacokinetic properties on a wide range of proteins.Likewise, fusions to human serum albumin can confer desirableproperties. Other types of fusion domains that may be selected includemultimerizing (e.g., dimerizing, tetramerizing) domains and functionaldomains.

As specific examples, the present disclosure provides fusion proteinscomprising variants of TβRII polypeptides fused to one of three Fcdomain sequences (e.g., SEQ ID NOs: 19, 20, and 21 as well as sequences85%, 90%, 91%, 92%, 93%, 94% 95%, 96%, 97%, 98%, 99%, or 100% identicalto SEQ ID NOs: 19, 20, and 21). Optionally, the Fc domain has one ormore mutations at residues such as Asp-265, Lys-322, and Asn-434(numbered in accordance with the corresponding full-length IgG). Incertain cases, the mutant Fc domain having one or more of thesemutations (e.g., Asp-265 mutation) has reduced ability of binding to theFey receptor relative to a wildtype Fc domain. In other cases, themutant Fc domain having one or more of these mutations (e.g., Asn-434mutation) has increased ability of binding to the MHC class I-relatedFc-receptor (FcRN) relative to a wildtype Fc domain.

It is understood that different elements of the fusion proteins may bearranged in any manner that is consistent with the desiredfunctionality. For example, a TβRII polypeptide may be placed C-terminalto a heterologous domain, or, alternatively, a heterologous domain maybe placed C-terminal to a TβRII polypeptide. The TβRII polypeptidedomain and the heterologous domain need not be adjacent in a fusionprotein, and additional domains or amino acid sequences may be includedC- or N-terminal to either domain or between the domains.

As used herein, the term “immunoglobulin Fc domain” or simply “Fe” isunderstood to mean the carboxyl-terminal portion of an immunoglobulinchain constant region, preferably an immunoglobulin heavy chain constantregion, or a portion thereof. For example, an immunoglobulin Fc regionmay comprise 1) a CH1 domain, a CH2 domain, and a CH3 domain, 2) a CH1domain and a CH2 domain, 3) a CH1 domain and a CH3 domain, 4) a CH2domain and a CH3 domain, or 5) a combination of two or more domains andan immunoglobulin hinge region. In a preferred embodiment theimmunoglobulin Fc region comprises at least an immunoglobulin hingeregion a CH2 domain and a CH3 domain, and preferably lacks the CH1domain.

In one embodiment, the class of immunoglobulin from which the heavychain constant region is derived is IgG (Igγ) (γ subclasses 1, 2, 3, or4). Other classes of immunoglobulin, IgA (Igα), IgD (Igδ), IgE (Igε) andIgM (Igμ), may be used. The choice of appropriate immunoglobulin heavychain constant region is discussed in detail in U.S. Pat. Nos. 5,541,087and 5,726,044. The choice of particular immunoglobulin heavy chainconstant region sequences from certain immunoglobulin classes andsubclasses to achieve a particular result is considered to be within thelevel of skill in the art. The portion of the DNA construct encoding theimmunoglobulin Fc region preferably comprises at least a portion of ahinge domain, and preferably at least a portion of a CH₃ domain of Fcgamma or the homologous domains in any of IgA, IgD, IgE, or IgM.

Furthermore, it is contemplated that substitution or deletion of aminoacids within the immunoglobulin heavy chain constant regions may beuseful in the practice of the methods and compositions disclosed herein.One example would be to introduce amino acid substitutions in the upperCH2 region to create an Fc variant with reduced affinity for Fcreceptors (Cole et al. (1997) J. Immunol. 159:3613).

The application further provides TβRII-Fc fusion proteins withengineered or variant Fc regions. Such antibodies and Fc fusion proteinsmay be useful, for example, in modulating effector functions, such as,antigen-dependent cytotoxicity (ADCC) and complement-dependentcytotoxicity (CDC). Additionally, the modifications may improve thestability of the antibodies and Fc fusion proteins. Amino acid sequencevariants of the antibodies and Fc fusion proteins are prepared byintroducing appropriate nucleotide changes into the DNA, or by peptidesynthesis. Such variants include, for example, deletions from, and/orinsertions into and/or substitutions of, residues within the amino acidsequences of the antibodies and Fc fusion proteins disclosed herein. Anycombination of deletion, insertion, and substitution is made to arriveat the final construct, provided that the final construct possesses thedesired characteristics. The amino acid changes also may alterpost-translational processes of the antibodies and Fc fusion proteins,such as changing the number or position of glycosylation sites.

Antibodies and Fc fusion proteins with reduced effector function may beproduced by introducing changes in the amino acid sequence, including,but are not limited to, the Ala-Ala mutation described by Bluestone etal. (see WO 94/28027 and WO 98/47531; also see Xu et al. 2000 CellImmunol 200; 16-26). Thus, in certain embodiments, antibodies and Fcfusion proteins of the disclosure with mutations within the constantregion including the Ala-Ala mutation may be used to reduce or abolisheffector function. According to these embodiments, antibodies and Fcfusion proteins may comprise a mutation to an alanine at position 234 ora mutation to an alanine at position 235, or a combination thereof. Inone embodiment, the antibody or Fc fusion protein comprises an IgG4framework, wherein the Ala-Ala mutation would describe a mutation(s)from phenylalanine to alanine at position 234 and/or a mutation fromleucine to alanine at position 235. In another embodiment, the antibodyor Fc fusion protein comprises an IgG1 framework, wherein the Ala-Alamutation would describe a mutation(s) from leucine to alanine atposition 234 and/or a mutation from leucine to alanine at position 235.The antibody or Fc fusion protein may alternatively or additionallycarry other mutations, including the point mutation K322A in the CH2domain (Hezareh et al. 2001 J Virol. 75: 12161-8).

In particular embodiments, the antibody or Fc fusion protein may bemodified to either enhance or inhibit complement dependent cytotoxicity(CDC). Modulated CDC activity may be achieved by introducing one or moreamino acid substitutions, insertions, or deletions in an Fc region (see,e.g., U.S. Pat. No. 6,194,551). Alternatively or additionally, cysteineresidue(s) may be introduced in the Fc region, thereby allowinginterchain disulfide bond formation in this region. The homodimericantibody thus generated may have improved or reduced internalizationcapability and/or increased or decreased complement-mediated cellkilling. See Caron et al., J. Exp Med. 176:1191-1195 (1992) and Shopes,B. J. Immunol. 148:2918-2922 (1992), WO99/51642, Duncan & Winter Nature322: 738-40 (1988); U.S. Pat. No. 5,648,260; U.S. Pat. No. 5,624,821;and WO94/29351.

In certain embodiments, the present disclosure makes available isolatedand/or purified forms of the TβRII polypeptides, which are isolatedfrom, or otherwise substantially free of (e.g., at least 80%, 90%, 95%,96%, 97%, 98%, or 99% free of), other proteins and/or other TβRIIpolypeptide species. TβRII polypeptides will generally be produced byexpression from recombinant nucleic acids.

In certain embodiments, the disclosure includes nucleic acids encodingsoluble TβRII polypeptides comprising the coding sequence for anextracellular portion of a TβRII protein. In further embodiments, thisdisclosure also pertains to a host cell comprising such nucleic acids.The host cell may be any prokaryotic or eukaryotic cell. For example, apolypeptide of the present disclosure may be expressed in bacterialcells such as E. coli, insect cells (e.g., using a baculovirusexpression system), yeast, or mammalian cells. Other suitable host cellsare known to those skilled in the art. Accordingly, some embodiments ofthe present disclosure further pertain to methods of producing the TβRIIpolypeptides.

B. Nucleic Acids Encoding TβRII Polypeptides

In certain aspects, the disclosure provides isolated and/or recombinantnucleic acids encoding any of the TβRII polypeptides, includingfragments, functional variants and fusion proteins disclosed herein. SEQID NO: 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, and 102 encode variantsof TβRII extracellular domain fused to an IgG2 Fc or an N-terminallytruncated IgG1 Fc domain. The subject nucleic acids may besingle-stranded or double stranded. Such nucleic acids may be DNA or RNAmolecules. These nucleic acids may be used, for example, in methods formaking TβRII polypeptides or as direct therapeutic agents (e.g., in anantisense, RNAi or gene therapy approach).

In certain aspects, the subject nucleic acids encoding TβRIIpolypeptides are further understood to include nucleic acids that arevariants of SEQ ID NOs: 26, 28, 30, 32, 34, 36, 38, 40, 42, 44 and 102.Variant nucleotide sequences include sequences that differ by one ormore nucleotide substitutions, additions or deletions, such as allelicvariants.

In certain embodiments, the disclosure provides isolated or recombinantnucleic acid sequences that are at least 80%, 85%, 90%, 91%, 92%, 93%,94% 95%, 96%, 97%, 98%, 99%, or 100% identical to SEQ ID NOs: 26, 28,30, 32, 34, 36, 38, 40, 42, 44, and 102. One of ordinary skill in theart will appreciate that nucleic acid sequences complementary to SEQ IDNOs: 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, and 102, and variants ofSEQ ID NOs: 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, and 102 are alsowithin the scope of this disclosure. In further embodiments, the nucleicacid sequences of the disclosure can be isolated, recombinant, and/orfused with a heterologous nucleotide sequence, or in a DNA library.

In other embodiments, nucleic acids of the disclosure also includenucleotide sequences that hybridize under highly stringent conditions tothe nucleotide sequences designated in SEQ ID NOs: 26, 28, 30, 32, 34,36, 38, 40, 42, 44, and 102 complement sequences of SEQ ID NOs: 26, 28,30, 32, 34, 36, 38, 40, 42, 44, and 102, or fragments thereof. Asdiscussed above, one of ordinary skill in the art will understandreadily that appropriate stringency conditions which promote DNAhybridization can be varied. For example, one could perform thehybridization at 6.0× sodium chloride/sodium citrate (SSC) at about 45°C., followed by a wash of 2.0×SSC at 50° C. For example, the saltconcentration in the wash step can be selected from a low stringency ofabout 2.0×SSC at 50° C. to a high stringency of about 0.2×SSC at 50° C.In addition, the temperature in the wash step can be increased from lowstringency conditions at room temperature, about 22° C., to highstringency conditions at about 65° C. Both temperature and salt may bevaried, or temperature or salt concentration may be held constant whilethe other variable is changed. In some embodiments, the disclosureprovides nucleic acids which hybridize under low stringency conditionsof 6×SSC at room temperature followed by a wash at 2×SSC at roomtemperature.

Isolated nucleic acids which differ from the nucleic acids as set forthin SEQ ID NOs: 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, and 102 due todegeneracy in the genetic code are also within the scope of thedisclosure. For example, a number of amino acids are designated by morethan one triplet. Codons that specify the same amino acid, or synonyms(for example, CAU and CAC are synonyms for histidine) may result in“silent” mutations which do not affect the amino acid sequence of theprotein. However, it is expected that DNA sequence polymorphisms that dolead to changes in the amino acid sequences of the subject proteins willexist among mammalian cells. One skilled in the art will appreciate thatthese variations in one or more nucleotides (up to about 3-5% of thenucleotides) of the nucleic acids encoding a particular protein mayexist among individuals of a given species due to natural allelicvariation. Any and all such nucleotide variations and resulting aminoacid polymorphisms are within the scope of this disclosure.

It will be appreciated by one of skill in the art that correspondingvariants based on the long isoform of TβRII will include nucleotidesequences encoding the 25-amino acid insertion along with a conservativeVal-Ile substitution at the flanking position C-terminal to theinsertion. It will also be appreciated that corresponding variants basedon either the long (A) or short (B) isoforms of TβRII will includevariant nucleotide sequences comprising an insertion of 108 nucleotides,encoding a 36-amino-acid insertion (SEQ ID NO: 18), at the same locationdescribed for naturally occurring TβRII isoform C (see Exemplification).

In certain embodiments, the recombinant nucleic acids of the disclosuremay be operably linked to one or more regulatory nucleotide sequences inan expression construct. Regulatory nucleotide sequences will generallybe appropriate to the host cell used for expression. Numerous types ofappropriate expression vectors and suitable regulatory sequences areknown in the art for a variety of host cells. Typically, said one ormore regulatory nucleotide sequences may include, but are not limitedto, promoter sequences, leader or signal sequences, ribosomal bindingsites, transcriptional start and termination sequences, translationalstart and termination sequences, and enhancer or activator sequences.Constitutive or inducible promoters as known in the art are contemplatedby the disclosure. The promoters may be either naturally occurringpromoters, or hybrid promoters that combine elements of more than onepromoter. An expression construct may be present in a cell on anepisome, such as a plasmid, or the expression construct may be insertedin a chromosome. In a preferred embodiment, the expression vectorcontains a selectable marker gene to allow the selection of transformedhost cells. Selectable marker genes are well known in the art and willvary with the host cell used.

In certain aspects disclosed herein, the subject nucleic acid isprovided in an expression vector comprising a nucleotide sequenceencoding a TβRII polypeptide and operably linked to at least oneregulatory sequence. Regulatory sequences are art-recognized and areselected to direct expression of the TβRII polypeptide. Accordingly, theterm regulatory sequence includes promoters, enhancers, and otherexpression control elements. Exemplary regulatory sequences aredescribed in Goeddel; Gene Expression Technology: Methods in Enzymology,Academic Press, San Diego, Calif. (1990). For instance, any of a widevariety of expression control sequences that control the expression of aDNA sequence when operatively linked to it may be used in these vectorsto express DNA sequences encoding a TβRII polypeptide. Such usefulexpression control sequences, include, for example, the early and latepromoters of SV40, tet promoter, adenovirus or cytomegalovirus immediateearly promoter, RSV promoters, the lac system, the trp system, the TACor TRC system, T7 promoter whose expression is directed by T7 RNApolymerase, the major operator and promoter regions of phage lambda, thecontrol regions for fd coat protein, the promoter for 3-phosphoglyceratekinase or other glycolytic enzymes, the promoters of acid phosphatase,e.g., Pho5, the promoters of the yeast α-mating factors, the polyhedronpromoter of the baculovirus system and other sequences known to controlthe expression of genes of prokaryotic or eukaryotic cells or theirviruses, and various combinations thereof. It should be understood thatthe design of the expression vector may depend on such factors as thechoice of the host cell to be transformed and/or the type of proteindesired to be expressed. Moreover, the vector's copy number, the abilityto control that copy number and the expression of any other proteinencoded by the vector, such as antibiotic markers, should also beconsidered.

A recombinant nucleic acid included in the disclosure can be produced byligating the cloned gene, or a portion thereof, into a vector suitablefor expression in either prokaryotic cells, eukaryotic cells (yeast,avian, insect or mammalian), or both. Expression vehicles for productionof a recombinant TβRII polypeptide include plasmids and other vectors.For instance, suitable vectors include plasmids of the types:pBR322-derived plasmids, pEMBL-derived plasmids, pEX-derived plasmids,pBTac-derived plasmids and pUC-derived plasmids for expression inprokaryotic cells, such as E. coli.

Some mammalian expression vectors contain both prokaryotic sequences tofacilitate the propagation of the vector in bacteria, and one or moreeukaryotic transcription units that are expressed in eukaryotic cells.The pcDNAI/amp, pcDNAI/neo, pRc/CMV, pSV2gpt, pSV2neo, pSV2-dhfr, pTk2,pRSVneo, pMSG, pSVT7, pko-neo and pHyg derived vectors are examples ofmammalian expression vectors suitable for transfection of eukaryoticcells. Some of these vectors are modified with sequences from bacterialplasmids, such as pBR322, to facilitate replication and drug resistanceselection in both prokaryotic and eukaryotic cells. Alternatively,derivatives of viruses such as the bovine papilloma virus (BPV-1), orEpstein-Barr virus (pHEBo, pREP-derived and p205) can be used fortransient expression of proteins in eukaryotic cells. Examples of otherviral (including retroviral) expression systems can be found below inthe description of gene therapy delivery systems. The various methodsemployed in the preparation of the plasmids and in transformation ofhost organisms are well known in the art. For other suitable expressionsystems for both prokaryotic and eukaryotic cells, as well as generalrecombinant procedures, see Molecular Cloning A Laboratory Manual, 3rdEd., ed. by Sambrook, Fritsch and Maniatis (Cold Spring HarborLaboratory Press, 2001). In some instances, it may be desirable toexpress the recombinant polypeptides by the use of a baculovirusexpression system. Examples of such baculovirus expression systemsinclude pVL-derived vectors (such as pVL1392, pVL1393 and pVL941),pAcUW-derived vectors (such as pAcUW1), and pBlueBac-derived vectors(such as the β-gal containing pBlueBac III).

In certain embodiments, a vector will be designed for production of thesubject TβRII polypeptides in CHO cells, such as a Pcmv-Script vector(Stratagene, La Jolla, Calif.), pcDNA4 vectors (Invitrogen, Carlsbad,Calif.) and pCI-neo vectors (Promega, Madison, Wis.). In a preferredembodiment, a vector will be designed for production of the subjectTβRII polypeptides in HEK-293 cells. As will be apparent, the subjectgene constructs can be used to cause expression of the subject TβRIIpolypeptides in cells propagated in culture, e.g., to produce proteins,including fusion proteins or variant proteins, for purification.

This disclosure also pertains to a host cell transfected with arecombinant gene including a coding sequence (e.g., SEQ ID NOs: 26, 28,30, 32, 34, 36, 38, 40, 42, 44, and 102) for one or more of the subjectTβRII polypeptides. The host cell may be any prokaryotic or eukaryoticcell. For example, a TβRII polypeptide disclosed herein may be expressedin bacterial cells such as E. coli, insect cells (e.g., using abaculovirus expression system), yeast, or mammalian cells. Othersuitable host cells are known to those skilled in the art.

Accordingly, the present disclosure further pertains to methods ofproducing the subject TβRII polypeptides. For example, a host celltransfected with an expression vector encoding a TβRII polypeptide canbe cultured under appropriate conditions to allow expression of theTβRII polypeptide to occur. The TβRII polypeptide may be secreted andisolated from a mixture of cells and medium containing the TβRIIpolypeptide. Alternatively, the TβRII polypeptide may be retainedcytoplasmically or in a membrane fraction and the cells harvested, lysedand the protein isolated. A cell culture includes host cells, and media.Suitable media for cell culture are well known in the art. The subjectTβRII polypeptides can be isolated from cell culture medium, host cells,or both, using techniques known in the art for purifying proteins,including ion-exchange chromatography, gel filtration chromatography,ultrafiltration, electrophoresis, immunoaffinity purification withantibodies specific for particular epitopes of the TβRII polypeptidesand affinity purification with an agent that binds to a domain fused tothe TβRII polypeptide (e.g., a protein A column may be used to purify aTβRII-Fc fusion). In a preferred embodiment, the TβRII polypeptide is afusion protein containing a domain which facilitates its purification.As an example, purification may be achieved by a series of columnchromatography steps, including, for example, three or more of thefollowing, in any order: protein A chromatography, Q sepharosechromatography, phenylsepharose chromatography, size exclusionchromatography, and cation exchange chromatography. The purificationcould be completed with viral filtration and buffer exchange.

In another embodiment, a fusion gene coding for a purification leadersequence, such as a poly-(His)/enterokinase cleavage site sequence atthe N-terminus of the desired portion of the recombinant TβRIIpolypeptide, can allow purification of the expressed fusion protein byaffinity chromatography using a Ni²⁺ metal resin. The purificationleader sequence can then be subsequently removed by treatment withenterokinase to provide the purified TβRII polypeptide (e.g., seeHochuli et al., (1987) J. Chromatography 411:177; and Janknecht et al.,PNAS USA 88:8972).

Techniques for making fusion genes are well known. Essentially, thejoining of various DNA fragments coding for different polypeptidesequences is performed in accordance with conventional techniques,employing blunt-ended or stagger-ended termini for ligation, restrictionenzyme digestion to provide for appropriate termini, filling-in ofcohesive ends as appropriate, alkaline phosphatase treatment to avoidundesirable joining, and enzymatic ligation. In another embodiment, thefusion gene can be synthesized by conventional techniques includingautomated DNA synthesizers. Alternatively, PCR amplification of genefragments can be carried out using anchor primers which give rise tocomplementary overhangs between two consecutive gene fragments which cansubsequently be annealed to generate a chimeric gene sequence (see, forexample, Current Protocols in Molecular Biology, eds. Ausubel et al.,John Wiley & Sons: 1992).

Examples of categories of nucleic acid compounds that are antagonists ofTβRII, TGFβ1, and TGFβ3 include antisense nucleic acids, RNAi constructsand catalytic nucleic acid constructs. A nucleic acid compound may besingle or double stranded. A double stranded compound may also includeregions of overhang or non-complementarity, where one or the other ofthe strands is single-stranded. A single-stranded compound may includeregions of self-complementarity, meaning that the compound forms aso-called “hairpin” or “stem-loop” structure, with a region of doublehelical structure. A nucleic acid compound may comprise a nucleotidesequence that is complementary to a region consisting of no more than1000, no more than 500, no more than 250, no more than 100 or no morethan 50, 35, 30, 25, 22, 20 or 18 nucleotides of the full-length TβRIInucleic acid sequence or ligand nucleic acid sequence. The region ofcomplementarity will preferably be at least 8 nucleotides, andoptionally at least 10 or at least 15 nucleotides, such as between 15and 25 nucleotides. A region of complementarity may fall within anintron, a coding sequence, or a noncoding sequence of the targettranscript, such as the coding sequence portion. Generally, a nucleicacid compound will have a length of about 8 to about 500 nucleotides orbase pairs in length, such as about 14 to about 50 nucleotides. Anucleic acid may be a DNA (particularly for use as an antisense), RNA,or RNA:DNA hybrid. Any one strand may include a mixture of DNA and RNA,as well as modified forms that cannot readily be classified as eitherDNA or RNA. Likewise, a double-stranded compound may be DNA:DNA, DNA:RNAor RNA:RNA, and any one strand may also include a mixture of DNA andRNA, as well as modified forms that cannot readily be classified aseither DNA or RNA. A nucleic acid compound may include any of a varietyof modifications, including one or modifications to the backbone (thesugar-phosphate portion in a natural nucleic acid, includinginternucleotide linkages) or the base portion (the purine or pyrimidineportion of a natural nucleic acid). An antisense nucleic acid compoundwill preferably have a length of about 15 to about 30 nucleotides andwill often contain one or more modifications to improve characteristicssuch as stability in the serum, in a cell or in a place where thecompound is likely to be delivered, such as the stomach in the case oforally delivered compounds and the lung for inhaled compounds. In thecase of an RNAi construct, the strand complementary to the targettranscript will generally be RNA or modifications thereof. The otherstrand may be RNA, DNA, or any other variation. The duplex portion ofdouble-stranded or single-stranded “hairpin” RNAi construct willpreferably have a length of 18 to 40 nucleotides in length andoptionally about 21 to 23 nucleotides in length, so long as it serves asa Dicer substrate. Catalytic or enzymatic nucleic acids may be ribozymesor DNA enzymes and may also contain modified forms. Nucleic acidcompounds may inhibit expression of the target by about 50%, 75%, 90%,or more when contacted with cells under physiological conditions and ata concentration where a nonsense or sense control has little or noeffect. Preferred concentrations for testing the effect of nucleic acidcompounds are 1, 5 and 10 micromolar. Nucleic acid compounds may also betested for effects on, for example, angiogenesis.

C. Antibody Antagonists

In certain aspects, a TβRII antagonist to be used in accordance with themethods and uses disclosed herein is an antibody (TβRII antagonistantibody) or combination of antibodies. A TβRII antagonist antibody, orcombination of antibodies, may inhibit and/or bind to, for example, oneor more TβRII ligands (e.g., TGFβ1, TGFβ2, and TGFβ3), TβRII receptor,TβRII-associated type I receptor (e.g., ALK5), and/or TβRII co-receptor(e.g., betaglycan). In some embodiments, the ability for a TβRIIantagonist antibody, or combination of antibody, to inhibit signaling(e.g., Smad signaling) and/or bind to a target is determined in an invitro or cell-based assay including, for example, those describedherein. As described herein, a TβRII antagonist antibody, or combinationof antagonist antibodies, may be used alone or in combination with oneor more additional supportive therapies or active agents to treat,prevent, or reduce the progression rate and/or severity of amyeloproliferative disorder (e.g., myelofibrosis, polycythemia vera, andessential thrombocythaemia) and/or a Janus kinase-associated disorder(e.g., a JAK2 kinase-associated disorder) or one or more complicationsof a myeloproliferative disorders and/or a Janus kinase-associateddisorder.

In certain embodiments, a TβRII antagonist antibody, or combination ofantibodies, is an antibody that inhibits at least TGFβ1. Therefore, insome embodiments, a TβRII antagonist antibody, or combination ofantibodies, binds to at least TGFβ1. As used herein, a TGFβ1 antibody(anti-TGFβ1 antibody) generally refers to an antibody that is capable ofbinding to TGFβ1 with sufficient affinity such that the antibody isuseful as a diagnostic and/or therapeutic agent in targeting TGFβ1. Incertain embodiments, the extent of binding of an anti-TGFβ1 antibody toan unrelated, non-TGFβ1 protein is less than about 10%, 9%, 8%, 7%, 6%,5%, 4%, 3%, 2%, or less than 1% of the binding of the antibody to TGFβ1as measured, for example, by a radioimmunoassay (MA). In certainembodiments, an anti-TGFβ1 antibody binds to an epitope of TGFβ1 that isconserved among TGFβ1 from different species. In certain preferredembodiments, an anti-TGFβ1 antibody binds to human TGFβ1. In someembodiments, a TGFβ1 antibody may inhibit TGFβ1 from binding to a typeI, type II, and/or co-receptor (e.g., TβRII, ALK5, and/or betaglycan)and thus inhibit TGFβ1 signaling (e.g., Smad signaling). It should benoted that TGFβ1 shares some sequence homology to TGFβ2 and TGFβ3.Therefore antibodies that bind TGFβ1, in some embodiments, may also bindto TGFβ2 and/or TGFβ3. In some embodiments, the disclosure relates to amultispecific antibody (e.g., bi-specific antibody), and uses thereof,that binds to TGFβ1 and further binds to, for example, one or moreadditional TβRII ligands (e.g., TGFβ2, TGFβ3, or TGFβ2 and TGFβ3), oneor more type I and/or type II receptors (e.g., TβRII and ALK5), and/orone or more co-receptors (e.g., betaglycan). In some embodiments, amultispecific antibody that binds to TGFβ1 does not bind or does notsubstantially bind to TGFβ2 (e.g., binds to TGFβ2 with a K_(D) ofgreater than 1×10⁻⁷ M or has relatively modest binding, e.g., about1×10⁻⁸M or about 1×10⁻⁹M). In some embodiments, a multispecific antibodythat binds to TGFβ1 further binds to TGFβ3 but does not bind or does notsubstantially bind to TGFβ2 (e.g., binds to TGFβ2 with a K_(D) ofgreater than 1×10⁻⁷ M or has relatively modest binding, e.g., about1×10⁻⁸M or about 1×10⁻⁹M). In some embodiments, the disclosure relatesto combinations of antibodies, and uses thereof, wherein the combinationof antibodies comprises a TGFβ1 antibody and one or more additionalantibodies that bind to, for example, one or more additional TβRIIligands (e.g., TGFβ2, TGFβ3, or TGFβ2 and TGFβ3), one or more type Iand/or type II receptors (e.g., TβRII and ALK5), and/or one or moreco-receptors (e.g., betaglycan). In some embodiments, a combination ofantibodies that comprises a TGFβ1 antibody does not comprise a TGFβ2antibody. In some embodiments, a combination of antibodies thatcomprises a TGFβ1 antibody further comprises a TGFβ3 antibody but doesnot comprise a TGFβ2 antibody.

In certain embodiments, a TβRII antagonist antibody, or combination ofantibodies, is an antibody that inhibits at least TGFβ2. Therefore, insome embodiments, a TβRII antagonist antibody, or combination ofantibodies, binds to at least TGFβ2. As used herein, a TGFβ2 antibody(anti-TGFβ2 antibody) generally refers to an antibody that is capable ofbinding to TGFβ2 with sufficient affinity such that the antibody isuseful as a diagnostic and/or therapeutic agent in targeting TGFβ2. Incertain embodiments, the extent of binding of an anti-TGFβ2 antibody toan unrelated, non-TGFβ2 protein is less than about 10%, 9%, 8%, 7%, 6%,5%, 4%, 3%, 2%, or less than 1% of the binding of the antibody to TGFβ2as measured, for example, by a radioimmunoassay (MA). In certainembodiments, an anti-TGFβ2 antibody binds to an epitope of TGFβ2 that isconserved among TGFβ2 from different species. In certain preferredembodiments, an anti-TGFβ2 antibody binds to human TGFβ2. In someembodiments, a TGFβ2 antibody may inhibit TGFβ2 from binding to a typeI, type II, and/or co-receptor (e.g., TβRII, ALK5, and/or betaglycan)and thus inhibit TGFβ2 signaling (e.g., Smad signaling). It should benoted that TGFβ2 shares some sequence homology to TGFβ1 and TGFβ3.Therefore antibodies that bind TGFβ2, in some embodiments, may also bindto TGFβ1 and/or TGFβ3. In some embodiments, the disclosure relates to amultispecific antibody (e.g., bi-specific antibody), and uses thereof,that binds to TGFβ2 and further binds to, for example, one or moreadditional TβRII ligands (e.g., TGFβ1, TGFβ3, or TGFβ1 and TGFβ3), oneor more type I and/or type II receptors (e.g., TβRII and ALK5), and/orone or more co-receptors (e.g., betaglycan) In some embodiments, thedisclosure relates to combinations of antibodies, and uses thereof,wherein the combination of antibodies comprises a TGFβ2 antibody and oneor more additional antibodies that bind to, for example, one or moreadditional TβRII ligands (e.g., TGFβ1, TGFβ3, or TGFβ1 and TGFβ3), oneor more type I and/or type II receptors (e.g., TβRII and ALK5), and/orone or more co-receptors (e.g., betaglycan).

In certain embodiments, a TβRII antagonist antibody, or combination ofantibodies, is an antibody that inhibits at least TGFβ3. Therefore, insome embodiments, a TβRII antagonist antibody, or combination ofantibodies, binds to at least TGFβ3. As used herein, a TGFβ3 antibody(anti-TGFβ3 antibody) generally refers to an antibody that is capable ofbinding to TGFβ3 with sufficient affinity such that the antibody isuseful as a diagnostic and/or therapeutic agent in targeting TGFβ3. Incertain embodiments, the extent of binding of an anti-TGFβ3 antibody toan unrelated, non-TGFβ3 protein is less than about 10%, 9%, 8%, 7%, 6%,5%, 4%, 3%, 2%, or less than 1% of the binding of the antibody to TGFβ3as measured, for example, by a radioimmunoassay (MA). In certainembodiments, an anti-TGFβ3 antibody binds to an epitope of TGFβ3 that isconserved among TGFβ3 from different species. In certain preferredembodiments, an anti-TGFβ3 antibody binds to human TGFβ3. In someembodiments, a TGFβ3 antibody may inhibit TGFβ3 from binding to a typeI, type II, and/or co-receptor (e.g., TβRII, ALK5, and/or betaglycan)and thus inhibit TGFβ3 signaling (e.g., Smad signaling). It should benoted that TGFβ3 shares some sequence homology to TGFβ2 and TGFβ1.Therefore antibodies that bind TGFβ3, in some embodiments, may also bindto TGFβ2 and/or TGFβ1. In some embodiments, the disclosure relates to amultispecific antibody (e.g., bi-specific antibody), and uses thereof,that binds to TGFβ3 and further binds to, for example, one or moreadditional TβRII ligands (e.g., TGFβ2, TGFβ1, or TGFβ2 and TGFβ1), oneor more type I and/or type II receptors (e.g., TβRII and ALK5), and/orone or more co-receptors (e.g., betaglycan). In some embodiments, amultispecific antibody that binds to TGFβ3 does not bind or does notsubstantially bind to TGFβ2 (e.g., binds to TGFβ2 with a K_(D) ofgreater than 1×10⁻⁷ M or has relatively modest binding, e.g., about1×10⁻⁸M or about 1×10⁻⁹M). In some embodiments, a multispecific antibodythat binds to TGFβ3 further binds to TGFβ1 but does not bind or does notsubstantially bind to TGFβ2 (e.g., binds to TGFβ2 with a K_(D) ofgreater than 1×10⁻⁷ M or has relatively modest binding, e.g., about1×10⁻⁸M or about 1×10⁻⁹M). In some embodiments, the disclosure relatesto combinations of antibodies, and uses thereof, wherein the combinationof antibodies comprises a TGFβ3 antibody and one or more additionalantibodies that bind to, for example, one or more additional TβRIIligands (e.g., TGFβ2, TGFβ1, or TGFβ2 and TGFβ1), one or more type Iand/or type II receptors (e.g., TβRII and ALK5), and/or one or moreco-receptors (e.g., betaglycan). In some embodiments, a combination ofantibodies that comprises a TGFβ3 antibody does not comprise a TGFβ2antibody. In some embodiments, a combination of antibodies thatcomprises a TGFβ3 antibody further comprises a TGFβ1 antibody but doesnot comprise a TGFβ2 antibody.

In certain aspects, a TβRII antagonist antibody, or combination ofantibodies, is an antibody that inhibits at least TβRII. Therefore, insome embodiments, a TβRII antagonist antibody, or combination ofantibodies, binds to at least TβRII. As used herein, a TβRII antibody(anti-TβRII antibody) generally refers to an antibody that binds toTβRII with sufficient affinity such that the antibody is useful as adiagnostic and/or therapeutic agent in targeting TβRII. In certainembodiments, the extent of binding of an anti-TβRII antibody to anunrelated, non-TβRII protein is less than about 10%, 9%, 8%, 7%, 6%, 5%,4%, 3%, 2%, or less than about 1% of the binding of the antibody toTβRII as measured, for example, by a radioimmunoassay (MA), Biacore, orother protein-protein interaction or binding affinity assay. In certainembodiments, an anti-TβRII antibody binds to an epitope of TβRII that isconserved among TβRII from different species. In certain preferredembodiments, an anti-TβRII antibody binds to human TβRII. In someembodiments, an anti-TβRII antibody may inhibit one or more TβRIIligands [e.g., TGFβ1; TGFβ2; TGFβ3; TGFβ1 and TGFβ3; TGFβ1 and TGFβ2;TGFβ2 and TGFβ3; or TGFβ1, TGFβ2, and TGFβ3] from binding to TβRII. Insome embodiments, an anti-TβRII antibody is a multispecific antibody(e.g., bi-specific antibody) that binds to TβRII and one or more TβRIIligands [e.g., TGFβ1, TGFβ2, and TGFβ3], type I receptor (e.g., ALK5),and/or co-receptor (e.g., betaglycan). In some embodiments, thedisclosure relates to combinations of antibodies, and uses thereof,wherein the combination of antibodies comprises an anti-TβRII antibodyand one or more additional antibodies that bind to, for example, one ormore TβRII ligands [e.g., TGFβ1, TGFβ2, and TGFβ3], type I receptors(e.g., ALK5), and/or co-receptor (e.g., betaglycan).

In certain aspects, a TβRII antagonist antibody, or combination ofantibodies, is an antibody that inhibits at least ALK5. Therefore, insome embodiments, a TβRII antagonist antibody, or combination ofantibodies, binds to at least ALK5. As used herein, an ALK5 antibody(anti-ALK5antibody) generally refers to an antibody that binds to ALK5with sufficient affinity such that the antibody is useful as adiagnostic and/or therapeutic agent in targeting ALK5. In certainembodiments, the extent of binding of an anti-ALK5 antibody to anunrelated, non-ALK5 protein is less than about 10%, 9%, 8%, 7%, 6%, 5%,4%, 3%, 2%, or less than about 1% of the binding of the antibody to ALK5as measured, for example, by a radioimmunoassay (MA), Biacore, or otherprotein-protein interaction or binding affinity assay. In certainembodiments, an anti-ALK5 antibody binds to an epitope of ALK5 that isconserved among ALK5 from different species. In certain preferredembodiments, an anti-ALK5 antibody binds to human ALK5. In someembodiments, an anti-ALK5 antibody may inhibit one or more TβRII ligands[e.g., TGFβ1; TGFβ2; TGFβ3; TGFβ1 and TGFβ3; TGFβ1 and TGFβ2; TGFβ2 andTGFβ3; or TGFβ1, TGFβ2, and TGFβ3] from binding to ALK5. In someembodiments, an anti-ALK5 antibody is a multispecific antibody (e.g.,bi-specific antibody) that binds to ALK5 and one or more TβRII ligands[e.g., TGFβ1, TGFβ2, and TGFβ3], type II receptor (e.g., TβRII), and/orco-receptor (e.g., betaglycan). In some embodiments, the disclosurerelates to combinations of antibodies, and uses thereof, wherein thecombination of antibodies comprises an anti-ALK5 antibody and one ormore additional antibodies that bind to, for example, one or more TβRIIligands [e.g., TGFβ1, TGFβ2, and TGFβ3], type II receptors (e.g.,TβRII), and/or co-receptor (e.g., betaglycan).

In certain aspects, a TβRII antagonist antibody, or combination ofantibodies, is an antibody that inhibits at least betaglycan. Therefore,in some embodiments, a TβRII antagonist antibody, or combination ofantibodies, binds to at least betaglycan. As used herein, a betaglycanantibody (anti-betaglycan antibody) generally refers to an antibody thatbinds to betaglycan with sufficient affinity such that the antibody isuseful as a diagnostic and/or therapeutic agent in targeting betaglycan.In certain embodiments, the extent of binding of an anti-betaglycanantibody to an unrelated, non-betaglycan protein is less than about 10%,9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, or less than about 1% of the binding ofthe antibody to betaglycan as measured, for example, by aradioimmunoassay (MA), Biacore, or other protein-protein interaction orbinding affinity assay. In certain embodiments, an anti-betaglycanantibody binds to an epitope of betaglycan that is conserved amongbetaglycan from different species. In certain preferred embodiments, ananti-betaglycan antibody binds to human betaglycan. In some embodiments,an anti-betaglycan antibody may inhibit one or more TβRII ligands [e.g.,TGFβ1; TGFβ2; TGFβ3; TGFβ1 and TGFβ3; TGFβ1 and TGFβ2; TGFβ2 and TGFβ3;or TGFβ1, TGFβ2, and TGFβ3] from binding to betaglycan. In someembodiments, an anti-betaglycan antibody is a multi specific antibody(e.g., bi-specific antibody) that binds to betaglycan and one or moreTβRII ligands [e.g., TGFβ1, TGFβ2, and TGFβ3], type I receptor (e.g.,ALK5), and/or type II receptors (e.g., TβRII). In some embodiments, thedisclosure relates to combinations of antibodies, and uses thereof,wherein the combination of antibodies comprises an anti-betaglycanantibody and one or more additional antibodies that bind to, forexample, one or more TβRII ligands [e.g., TGFβ1, TGFβ2, and TGFβ3], typeI receptors (e.g., ALK5), and/or type II receptors (e.g., TβRII).

The term antibody is used herein in the broadest sense and encompassesvarious antibody structures, including but not limited to monoclonalantibodies, polyclonal antibodies, multispecific antibodies (e.g.,bispecific antibodies), and antibody fragments so long as they exhibitthe desired antigen-binding activity. An antibody fragment refers to amolecule other than an intact antibody that comprises a portion of anintact antibody that binds the antigen to which the intact antibodybinds. Examples of antibody fragments include but are not limited to Fv,Fab, Fab′, Fab′-SH, F(ab′)₂; diabodies; linear antibodies; single-chainantibody molecules (e.g., scFv); and multispecific antibodies formedfrom antibody fragments. See, e.g., Hudson et al. (2003) Nat. Med.9:129-134; Pluckthun, in The Pharmacology of Monoclonal Antibodies, vol.113, Rosenburg and Moore eds., (Springer-Verlag, New York), pp. 269-315(1994); WO 93/16185; and U.S. Pat. Nos. 5,571,894, 5,587,458, and5,869,046. Antibodies disclosed herein may be polyclonal antibodies ormonoclonal antibodies. In certain embodiments, the antibodies of thepresent disclosure comprise a label attached thereto and able to bedetected (e.g., the label can be a radioisotope, fluorescent compound,enzyme, or enzyme co-factor). In preferred embodiments, the antibodiesof the present disclosure are isolated antibodies. Diabodies areantibody fragments with two antigen-binding sites that may be bivalentor bispecific. See, e.g., EP 404,097; WO 1993/01161; Hudson et al.(2003) Nat. Med. 9:129-134 (2003); and Hollinger et al. (1993) Proc.Natl. Acad. Sci. USA 90: 6444-6448. Triabodies and tetrabodies are alsodescribed in Hudson et al. (2003) Nat. Med. 9:129-134. Single-domainantibodies are antibody fragments comprising all or a portion of theheavy-chain variable domain or all or a portion of the light-chainvariable domain of an antibody. In certain embodiments, a single-domainantibody is a human single-domain antibody. See, e.g., U.S. Pat. No.6,248,516. Antibody fragments can be made by various techniques,including but not limited to proteolytic digestion of an intact antibodyas well as production by recombinant host cells (e.g., E. coli orphage), as described herein.

The antibodies herein may be of any class. The class of an antibodyrefers to the type of constant domain or constant region possessed byits heavy chain. There are five major classes of antibodies: IgA, IgD,IgE, IgG, and IgM, and several of these may be further divided intosubclasses (isotypes), for example, IgG₁, IgG₂, IgG₃, IgG₄, IgA₁, andIgA₂. The heavy-chain constant domains that correspond to the differentclasses of immunoglobulins are called alpha, delta, epsilon, gamma, andmu.

In general, an antibody for use in the methods disclosed hereinspecifically binds to its target antigen, preferably with high bindingaffinity. Affinity may be expressed as a K_(D) value and reflects theintrinsic binding affinity (e.g., with minimized avidity effects).Typically, binding affinity is measured in vitro, whether in a cell-freeor cell-associated setting. Any of a number of assays known in the art,including those disclosed herein, can be used to obtain binding affinitymeasurements including, for example, surface plasmon resonance (Biacore™assay), radiolabeled antigen binding assay (MA), and ELISA. In someembodiments, antibodies of the present disclosure bind to their targetantigens (e.g. TGFβ1, TGFβ2, TGFβ2, ALK5, betaglycan, and TβRII.) withat least a K_(D) Of 1×10⁻⁷ or stronger, 1×10⁻⁸ or stronger, 1×10⁻⁹ orstronger, 1×10⁻¹⁰ or stronger, 1×10⁻¹¹ or stronger, 1×10⁻¹² or stronger,1×10⁻¹³ or stronger, or 1×10⁻¹⁴ or stronger.

In certain embodiments, K_(D) is measured by RIA performed with the Fabversion of an antibody of interest and its target antigen as describedby the following assay. Solution binding affinity of Fabs for theantigen is measured by equilibrating Fab with a minimal concentration ofradiolabeled antigen (e.g., ¹²⁵I-labeled) in the presence of a titrationseries of unlabeled antigen, then capturing bound antigen with ananti-Fab antibody-coated plate [see, e.g., Chen et al. (1999) J. Mol.Biol. 293:865-881]. To establish conditions for the assay, multi-wellplates (e.g., MICROTITER® from Thermo Scientific) are coated (e.g.,overnight) with a capturing anti-Fab antibody (e.g., from Cappel Labs)and subsequently blocked with bovine serum albumin, preferably at roomtemperature (e.g., approximately 23° C.). In a non-adsorbent plate,radiolabeled antigen are mixed with serial dilutions of a Fab ofinterest [e.g., consistent with assessment of the anti-VEGF antibody,Fab-12, in Presta et al., (1997) Cancer Res. 57:4593-4599]. The Fab ofinterest is then incubated, preferably overnight but the incubation maycontinue for a longer period (e.g., about 65 hours) to ensure thatequilibrium is reached. Thereafter, the mixtures are transferred to thecapture plate for incubation, preferably at room temperature for aboutone hour. The solution is then removed and the plate is washed timesseveral times, preferably with polysorbate 20 and PBS mixture. When theplates have dried, scintillant (e.g., MICROSCINT® from Packard) isadded, and the plates are counted on a gamma counter (e.g., TOPCOUNT®from Packard).

According to another embodiment, K_(D) is measured using surface plasmonresonance assays using, for example a BIACORE® 2000 or a BIACORE® 3000(Biacore, Inc., Piscataway, N.J.) with immobilized antigen CM5 chips atabout 10 response units (RU). Briefly, carboxymethylated dextranbiosensor chips (CM5, Biacore, Inc.) are activated withN-ethyl-N′-(3-dimethylaminopropyl)-carbodiimide hydrochloride (EDC) andN-hydroxysuccinimide (NETS) according to the supplier's instructions.For example, an antigen can be diluted with 10 mM sodium acetate, pH4.8, to 5 μg/ml (about 0.2 μM) before injection at a flow rate of 5μ1/minute to achieve approximately 10 response units (RU) of coupledprotein. Following the injection of antigen, 1 M ethanolamine isinjected to block unreacted groups. For kinetics measurements, two-foldserial dilutions of Fab (0.78 nM to 500 nM) are injected in PBS with0.05% polysorbate 20 (TWEEN-20®) surfactant (PBST) at at a flow rate ofapproximately 25 μl/min. Association rates (k_(on)) and dissociationrates (k_(off)) are calculated using, for example, a simple one-to-oneLangmuir binding model (BIACORE® Evaluation Software version 3.2) bysimultaneously fitting the association and dissociation sensorgrams. Theequilibrium dissociation constant (K_(D)) is calculated as the ratiok_(off)/k_(on) [see, e.g., Chen et al., (1999) J. Mol. Biol.293:865-881]. If the on-rate exceeds, for example, 10⁶ M⁻¹ s⁻¹ by thesurface plasmon resonance assay above, then the on-rate can bedetermined by using a fluorescent quenching technique that measures theincrease or decrease in fluorescence emission intensity (e.g.,excitation=295 nm; emission=340 nm, 16 nm band-pass) of a 20 nManti-antigen antibody (Fab form) in PBS in the presence of increasingconcentrations of antigen as measured in a spectrometer, such as astop-flow equipped spectrophometer (Aviv Instruments) or a 8000-seriesSLM-AMINCO® spectrophotometer (ThermoSpectronic) with a stirred cuvette.

The nucleic acid and amino acid sequences of TβRII, ALK5, betaglycan,TGFβ1, TGFβ2, and TGFβ3, particularly human sequences, are well known inthe art and thus antibody antagonists for use in accordance with thisdisclosure may be routinely made by the skilled artisan based on theknowledge in the art and teachings provided herein.

In certain embodiments, an antibody provided herein is a chimericantibody. A chimeric antibody refers to an antibody in which a portionof the heavy and/or light chain is derived from a particular source orspecies, while the remainder of the heavy and/or light chain is derivedfrom a different source or species. Certain chimeric antibodies aredescribed, for example, in U.S. Pat. No. 4,816,567; and Morrison et al.,(1984) Proc. Natl. Acad. Sci. USA, 81:6851-6855. In some embodiments, achimeric antibody comprises a non-human variable region (e.g., avariable region derived from a mouse, rat, hamster, rabbit, or non-humanprimate, such as a monkey) and a human constant region. In someembodiments, a chimeric antibody is a “class switched” antibody in whichthe class or subclass has been changed from that of the parent antibody.In general, chimeric antibodies include antigen-binding fragmentsthereof.

In certain embodiments, a chimeric antibody provided herein is ahumanized antibody. A humanized antibody refers to a chimeric antibodycomprising amino acid residues from non-human hypervariable regions(HVRs) and amino acid residues from human framework regions (FRs). Incertain embodiments, a humanized antibody will comprise substantiallyall of at least one, and typically two, variable domains, in which allor substantially all of the HVRs (e.g., CDRs) correspond to those of anon-human antibody, and all or substantially all of the FRs correspondto those of a human antibody. A humanized antibody optionally maycomprise at least a portion of an antibody constant region derived froma human antibody. A “humanized form” of an antibody, e.g., a non-humanantibody, refers to an antibody that has undergone humanization.

Humanized antibodies and methods of making them are reviewed, forexample, in Almagro and Fransson (2008) Front. Biosci. 13:1619-1633 andare further described, for example, in Riechmann et al., (1988) Nature332:323-329; Queen et al. (1989) Proc. Nat'l Acad. Sci. USA86:10029-10033; U.S. Pat. Nos. 5,821,337, 7,527,791, 6,982,321, and7,087,409; Kashmiri et al., (2005) Methods 36:25-34 [describing SDR(a-CDR) grafting]; Padlan, Mol. Immunol. (1991) 28:489-498 (describing“resurfacing”); Dall'Acqua et al. (2005) Methods 36:43-60 (describing“FR shuffling”); Osbourn et al. (2005) Methods 36:61-68; and Klimka etal. Br. J. Cancer (2000) 83:252-260 (describing the “guided selection”approach to FR shuffling).

Human framework regions that may be used for humanization include butare not limited to: framework regions selected using the “best-fit”method [see, e.g., Sims et al. (1993) J. Immunol. 151:2296]; frameworkregions derived from the consensus sequence of human antibodies of aparticular subgroup of light-chain or heavy-chain variable regions [see,e.g., Carter et al. (1992) Proc. Natl. Acad. Sci. USA, 89:4285; andPresta et al. (1993) J. Immunol., 151:2623]; human mature (somaticallymutated) framework regions or human germline framework regions [see,e.g., Almagro and Fransson (2008) Front. Biosci. 13:1619-1633]; andframework regions derived from screening FR libraries [see, e.g., Bacaet cd., (1997) J. Biol. Chem. 272:10678-10684; and Rosok et cd., (1996)J. Biol. Chem. 271:22611-22618].

In certain embodiments, an antibody provided herein is a human antibody.Human antibodies can be produced using various techniques known in theart. Human antibodies are described generally in van Dijk and van deWinkel (2001) Curr. Opin. Pharmacol. 5: 368-74 and Lonberg (2008) Curr.Opin. Immunol. 20:450-459.

Human antibodies may be prepared by administering an immunogen (e.g aTβRII, ALK5, betaglycan, TGFβ1, TGFβ2, or TGFβ3 polypeptide) to atransgenic animal that has been modified to produce intact humanantibodies or intact antibodies with human variable regions in responseto antigenic challenge. Such animals typically contain all or a portionof the human immunoglobulin loci, which replace the endogenousimmunoglobulin loci, or which are present extrachromosomally orintegrated randomly into the animal's chromosomes. In such transgenicanimals, the endogenous immunoglobulin loci have generally beeninactivated. For a review of methods for obtaining human antibodies fromtransgenic animals, see, for example, Lonberg (2005) Nat. Biotechnol.23:1117-1125; U.S. Pat. Nos. 6,075,181 and 6,150,584 (describingXENOMOUSE™ technology); U.S. Pat. No. 5,770,429 (describing HuMab®technology); U.S. Pat. No. 7,041,870 (describing K-M MOUSE® technology);and U.S. Patent Application Publication No. 2007/0061900 (describingVelociMouse® technology). Human variable regions from intact antibodiesgenerated by such animals may be further modified, for example, bycombining with a different human constant region.

Human antibodies provided herein can also be made by hybridoma-basedmethods.

Human myeloma and mouse-human heteromyeloma cell lines for theproduction of human monoclonal antibodies have been described [see,e.g., Kozbor J. Immunol., (1984) 133: 3001; Brodeur et al. (1987)Monoclonal Antibody Production Techniques and Applications, pp. 51-63,Marcel Dekker, Inc., New York; and Boerner et al. (1991) J. Immunol.,147: 86]. Human antibodies generated via human B-cell hybridomatechnology are also described in Li et al., (2006) Proc. Natl. Acad.Sci. USA, 103:3557-3562. Additional methods include those described, forexample, in U.S. Pat. No. 7,189,826 (describing production of monoclonalhuman IgM antibodies from hybridoma cell lines) and Ni, XiandaiMianyixue (2006) 26(4):265-268 (2006) (describing human-humanhybridomas). Human hybridoma technology (Trioma technology) is alsodescribed in Vollmers and Brandlein (2005) Histol. Histopathol.,20(3):927-937 (2005) and Vollmers and Brandlein (2005) Methods Find Exp.Clin. Pharmacol., 27(3):185-91.

Human antibodies provided herein may also be generated by isolating Fvclone variable-domain sequences selected from human-derived phagedisplay libraries. Such variable-domain sequences may then be combinedwith a desired human constant domain. Techniques for selecting humanantibodies from antibody libraries are described herein.

For example, antibodies of the present disclosure may be isolated byscreening combinatorial libraries for antibodies with the desiredactivity or activities. A variety of methods are known in the art forgenerating phage-display libraries and screening such libraries forantibodies possessing the desired binding characteristics. Such methodsare reviewed, for example, in Hoogenboom et al. (2001) in Methods inMolecular Biology 178:1-37, O'Brien et al., ed., Human Press, Totowa,N.J. and further described, for example, in the McCafferty et al. (1991)Nature 348:552-554; Clackson et al., (1991) Nature 352: 624-628; Markset al. (1992) J. Mol. Biol. 222:581-597; Marks and Bradbury (2003) inMethods in Molecular Biology 248:161-175, Lo, ed., Human Press, Totowa,N.J.; Sidhu et al. (2004) J. Mol. Biol. 338(2):299-310; Lee et al.(2004) J. Mol. Biol. 340(5):1073-1093; Fellouse (2004) Proc. Natl. Acad.Sci. USA 101(34):12467-12472; and Lee et al. (2004) J. Immunol. Methods284(1-2): 119-132.

In certain phage display methods, repertoires of VH and VL genes areseparately cloned by polymerase chain reaction (PCR) and recombinedrandomly in phage libraries, which can then be screened forantigen-binding phage as described in Winter et al. (1994) Ann. Rev.Immunol., 12: 433-455. Phage typically display antibody fragments,either as single-chain Fv (scFv) fragments or as Fab fragments.Libraries from immunized sources provide high-affinity antibodies to theimmunogen (e.g., a TβRII, TGFβ1, TGFβ2, or TGFβ3 polypeptide) withoutthe requirement of constructing hybridomas. Alternatively, the naiverepertoire can be cloned (e.g., from human) to provide a single sourceof antibodies directed against a wide range of non-self and alsoself-antigens without any immunization as described by Griffiths et al.(1993) EMBO J, 12: 725-734. Finally, naive libraries can also be madesynthetically by cloning un-rearranged V-gene segments from stem cellsand using PCR primers containing random sequence to encode the highlyvariable CDR3 regions and to accomplish rearrangement in vitro, asdescribed by Hoogenboom and Winter (1992) J. Mol. Biol., 227: 381-388.Patent publications describing human antibody phage libraries include,for example: U.S. Pat. No. 5,750,373, and U.S. Patent Publication Nos.2005/0079574, 2005/0119455, 2005/0266000, 2007/0117126, 2007/0160598,2007/0237764, 2007/0292936, and 2009/0002360.

In certain embodiments, an antibody provided herein is a multispecificantibody, for example, a bispecific antibody. Multispecific antibodies(typically monoclonal antibodies) have binding specificities for atleast two different epitopes (e.g., two, three, four, five, or six ormore) on one or more (e.g., two, three, four, five, six or more)antigens.

Engineered antibodies with three or more functional antigen bindingsites, including “octopus antibodies,” are also included herein (see,e.g., US 2006/0025576A1).

In certain embodiments, the antibodies disclosed herein are monoclonalantibodies. Monoclonal antibody refers to an antibody obtained from apopulation of substantially homogeneous antibodies, i.e., the individualantibodies comprising the population are identical and/or bind the sameepitope, except for possible variant antibodies, e.g., containingnaturally occurring mutations or arising during production of amonoclonal antibody preparation, such variants generally being presentin minor amounts. In contrast to polyclonal antibody preparations, whichtypically include different antibodies directed against differentepitopes, each monoclonal antibody of a monoclonal antibody preparationis directed against a single epitope on an antigen. Thus, the modifier“monoclonal” indicates the character of the antibody as being obtainedfrom a substantially homogeneous population of antibodies and is not tobe construed as requiring production of the antibody by any particularmethod. For example, the monoclonal antibodies to be used in accordancewith the present methods may be made by a variety of techniques,including but not limited to the hybridoma method, recombinant DNAmethods, phage-display methods, and methods utilizing transgenic animalscontaining all or part of the human immunoglobulin loci, such methodsand other exemplary methods for making monoclonal antibodies beingdescribed herein.

For example, by using immunogens derived from TβRII,anti-protein/anti-peptide antisera or monoclonal antibodies can be madeby standard protocols [see, e.g., Antibodies: A Laboratory Manual (1988)ed. by Harlow and Lane, Cold Spring Harbor Press]. A mammal, such as amouse, hamster, or rabbit can be immunized with an immunogenic form ofthe TβRII polypeptide, an antigenic fragment which is capable ofeliciting an antibody response, or a fusion protein. Techniques forconferring immunogenicity on a protein or peptide include conjugation tocarriers or other techniques well known in the art. An immunogenicportion of a TβRII polypeptide can be administered in the presence ofadjuvant. The progress of immunization can be monitored by detection ofantibody titers in plasma or serum. Standard ELISA or other immunoassayscan be used with the immunogen as antigen to assess the levels ofantibody production and/or level of binding affinity.

Following immunization of an animal with an antigenic preparation ofTβRII, antisera can be obtained and, if desired, polyclonal antibodiescan be isolated from the serum. To produce monoclonal antibodies,antibody-producing cells (lymphocytes) can be harvested from animmunized animal and fused by standard somatic cell fusion procedureswith immortalizing cells such as myeloma cells to yield hybridoma cells.Such techniques are well known in the art, and include, for example, thehybridoma technique [see, e.g., Kohler and Milstein (1975) Nature, 256:495-497], the human B cell hybridoma technique [see, e.g., Kozbar et al.(1983) Immunology Today, 4:72], and the EBV-hybridoma technique toproduce human monoclonal antibodies [Cole et al. (1985) MonoclonalAntibodies and Cancer Therapy, Alan R. Liss, Inc. pp. 77-96]. Hybridomacells can be screened immunochemically for production of antibodiesspecifically reactive with a TβRII polypeptide, and monoclonalantibodies isolated from a culture comprising such hybridoma cells.

In certain embodiments, one or more amino acid modifications may beintroduced into the Fc region of an antibody provided herein therebygenerating an Fc-region variant. The Fc-region variant may comprise ahuman Fc-region sequence (e.g., a human IgG1, IgG2, IgG3 or IgG4 Fcregion) comprising an amino acid modification (e.g., a substitution,deletion, and/or addition) at one or more amino acid positions.

For example, the present disclosure contemplates an antibody variantthat possesses some but not all effector functions, which make it adesirable candidate for applications in which the half-life of theantibody in vivo is important yet for which certain effector functions[e.g., complement-dependent cytotoxicity (CDC) and antibody-dependentcellular cytotoxicity (ADCC)] are unnecessary or deleterious. In vitroand/or in vivo cytotoxicity assays can be conducted to confirm thereduction/depletion of CDC and/or ADCC activities. For example, Fcreceptor (FcR) binding assays can be conducted to ensure that theantibody lacks FcγR binding (hence likely lacking ADCC activity), butretains FcRn binding ability. The primary cells for mediating ADCC, NKcells, express FcγRIII only, whereas monocytes express FcγRI, FcγRII andFcγRIII. FcR expression on hematopoietic cells is summarized in, forexample, Ravetch and Kinet (1991) Annu. Rev. Immunol. 9:457-492.Non-limiting examples of in vitro assays to assess ADCC activity of amolecule of interest are described in U.S. Pat. No. 5,500,362;Hellstrom, I. et al. (1986) Proc. Nat'l Acad. Sci. USA 83:7059-7063;Hellstrom, I et al. (1985) Proc. Nat'l Acad. Sci. USA 82:1499-1502; U.S.Pat. No. 5,821,337; and Bruggemann, M. et al. (1987) J. Exp. Med.166:1351-1361. Alternatively, non-radioactive assay methods may beemployed (e.g., ACTI™, non-radioactive cytotoxicity assay for flowcytometry; CellTechnology, Inc. Mountain View, Calif.; and CytoTox 96®non-radioactive cytotoxicity assay, Promega, Madison, Wis.). Usefuleffector cells for such assays include peripheral blood mononuclearcells (PBMC) and natural killer (NK) cells. Alternatively, oradditionally, ADCC activity of the molecule of interest may be assessedin vivo, for example, in an animal model such as that disclosed inClynes et al. (1998) Proc. Nat'l Acad. Sci. USA 95:652-656. C1q bindingassays may also be carried out to confirm that the antibody is unable tobind C1q and hence lacks CDC activity [see, e.g., C1q and C3c bindingELISA in WO 2006/029879 and WO 2005/100402]. To assess complementactivation, a CDC assay may be performed [see, e.g., Gazzano-Santoro etal. (1996) J. Immunol. Methods 202:163; Cragg, M. S. et al. (2003) Blood101:1045-1052; and Cragg, M. S, and M. J. Glennie (2004) Blood103:2738-2743]. FcRn binding and in vivo clearance/half-lifedeterminations can also be performed using methods known in the art[see, e.g., Petkova, S. B. et al. (2006) Int. Immunol.18(12):1759-1769].

Antibodies of the present disclosure with reduced effector functioninclude those with substitution of one or more of Fc region residues238, 265, 269, 270, 297, 327 and 329 (U.S. Pat. No. 6,737,056). Such Fcmutants include Fc mutants with substitutions at two or more of aminoacid positions 265, 269, 270, 297 and 327, including the so-called“DANA” Fc mutant with substitution of residues 265 and 297 to alanine(U.S. Pat. No. 7,332,581).

In certain embodiments, it may be desirable to createcysteine-engineered antibodies, e.g., “thioMAbs,” in which one or moreresidues of an antibody are substituted with cysteine residues. Inparticular embodiments, the substituted residues occur at accessiblesites of the antibody. By substituting those residues with cysteine,reactive thiol groups are thereby positioned at accessible sites of theantibody and may be used to conjugate the antibody to other moieties,such as drug moieties or linker-drug moieties, to create animmunoconjugate, as described further herein. In certain embodiments,any one or more of the following residues may be substituted withcysteine: V205 (Kabat numbering) of the light chain; A118 (EU numbering)of the heavy chain; and S400 (EU numbering) of the heavy-chain Fcregion. Cysteine engineered antibodies may be generated as described,for example, in U.S. Pat. No. 7,521,541.

In addition, the techniques used to screen antibodies in order toidentify a desirable antibody may influence the properties of theantibody obtained. For example, if an antibody is to be used for bindingan antigen in solution, it may be desirable to test solution binding. Avariety of different techniques are available for testing interactionbetween antibodies and antigens to identify particularly desirableantibodies. Such techniques include ELISAs, surface plasmon resonancebinding assays (e.g., the Biacore™ binding assay, Biacore AB, Uppsala,Sweden), sandwich assays (e.g., the paramagnetic bead system of IGENInternational, Inc., Gaithersburg, Md.), western blots,immunoprecipitation assays, and immunohistochemistry.

In certain embodiments, amino acid sequence variants of the antibodiesand/or the binding polypeptides provided herein are contemplated. Forexample, it may be desirable to improve the binding affinity and/orother biological properties of the antibody and/or binding polypeptide.Amino acid sequence variants of an antibody and/or binding polypeptidesmay be prepared by introducing appropriate modifications into thenucleotide sequence encoding the antibody and/or binding polypeptide, orby peptide synthesis. Such modifications include, for example, deletionsfrom, and/or insertions into, and/or substitutions of residues within,the amino acid sequences of the antibody and/or binding polypeptide. Anycombination of deletion, insertion, and substitution can be made toarrive at the final construct, provided that the final constructpossesses the desired characteristics, e.g., target-binding (TβRII,ALK5, betaglycan, TGFβ1, TGFβ2, and/or TGFβ3).

Alterations (e.g., substitutions) may be made in HVRs, for example, toimprove antibody affinity. Such alterations may be made in HVR“hotspots,” i.e., residues encoded by codons that undergo mutation athigh frequency during the somatic maturation process (see, e.g.,Chowdhury (2008) Methods Mol. Biol. 207:179-196 (2008)), and/or SDRs(a-CDRs), with the resulting variant VH or VL being tested for bindingaffinity. Affinity maturation by constructing and reselecting fromsecondary libraries has been described in the art [see, e.g., Hoogenboomet al., in Methods in Molecular Biology 178:1-37, O'Brien et al., ed.,Human Press, Totowa, N.J., (2001)]. In some embodiments of affinitymaturation, diversity is introduced into the variable genes chosen formaturation by any of a variety of methods (e.g., error-prone PCR, chainshuffling, or oligonucleotide-directed mutagenesis). A secondary libraryis then created. The library is then screened to identify any antibodyvariants with the desired affinity. Another method to introducediversity involves HVR-directed approaches, in which several HVRresidues (e.g., 4-6 residues at a time) are randomized. HVR residuesinvolved in antigen binding may be specifically identified, e.g., usingalanine scanning mutagenesis or modeling. CDR-H3 and CDR-L3 inparticular are often targeted.

In certain embodiments, substitutions, insertions, or deletions mayoccur within one or more HVRs so long as such alterations do notsubstantially reduce the ability of the antibody to bind to the antigen.For example, conservative alterations (e.g., conservative substitutionsas provided herein) that do not substantially reduce binding affinitymay be made in HVRs. Such alterations may be outside of HVR “hotspots”or SDRs. In certain embodiments of the variant VH and VL sequencesprovided above, each HVR either is unaltered, or contains no more thanone, two, or three amino acid substitutions.

A useful method for identification of residues or regions of theantibody and/or the binding polypeptide that may be targeted formutagenesis is called “alanine scanning mutagenesis”, as described byCunningham and Wells (1989) Science, 244:1081-1085. In this method, aresidue or group of target residues (e.g., charged residues such as arg,asp, his, lys, and glu) are identified and replaced by a neutral ornegatively charged amino acid (e.g., alanine or polyalanine) todetermine whether the interaction of the antibody or binding polypeptidewith antigen is affected. Further substitutions may be introduced at theamino acid locations demonstrating functional sensitivity to the initialsubstitutions. Alternatively, or additionally, a crystal structure of anantigen-antibody complex can be used to identify contact points betweenthe antibody and antigen. Such contact residues and neighboring residuesmay be targeted or eliminated as candidates for substitution. Variantsmay be screened to determine whether they contain the desiredproperties.

Amino-acid sequence insertions include amino- and/or carboxyl-terminalfusions ranging in length from one residue to polypeptides containing ahundred or more residues, as well as intrasequence insertions of singleor multiple amino acid residues. Examples of terminal insertions includean antibody with an N-terminal methionyl residue. Other insertionalvariants of the antibody molecule include fusion of the N- or C-terminusof the antibody to an enzyme (e.g., for ADEPT) or a polypeptide whichincreases the serum half-life of the antibody.

In certain embodiments, an antibody and/or binding polypeptide providedherein may be further modified to contain additional non-proteinaceousmoieties that are known in the art and readily available. The moietiessuitable for derivatization of the antibody and/or binding polypeptideinclude but are not limited to water-soluble polymers. Non-limitingexamples of water-soluble polymers include, but are not limited to,polyethylene glycol (PEG), copolymers of ethylene glycol/propyleneglycol, carboxymethylcellulose, dextran, polyvinyl alcohol, polyvinylpyrrolidone, poly-1,3-dioxolane, poly-1,3,6-trioxane, ethylene/maleicanhydride copolymer, polyaminoacids (either homopolymers or randomcopolymers), and dextran or poly(n-vinyl pyrrolidone)polyethyleneglycol, propropylene glycol homopolymers, prolypropylene oxide/ethyleneoxide co-polymers, polyoxyethylated polyols (e.g., glycerol), polyvinylalcohol, and mixtures thereof. Polyethylene glycol propionaldehyde mayhave advantages in manufacturing due to its stability in water. Thepolymer may be of any molecular weight, and may be branched orunbranched. The number of polymers attached to the antibody and/orbinding polypeptide may vary, and if more than one polymer are attached,they can be the same or different molecules. In general, the numberand/or type of polymers used for derivatization can be determined basedon considerations including, but not limited to, the particularproperties or functions of the antibody and/or binding polypeptide to beimproved, whether the antibody derivative and/or binding polypeptidederivative will be used in a therapy under defined conditions.

Any of the TβRII antagonist antibodies disclosed herein can be combinedwith one or more additional TβRII antagonists to achieve the desiredeffect [to treat, prevent, or reduce the progression rate and/orseverity of a myelodysplastic disorder or one or more complications of amyelodysplastic disorder]. For example, a TβRII antagonist antibody canbe used in combination with i) one or more additional TβRII antagonistantibodies, ii) one or more TβRII polypeptides including variantsthereof; iii) one or more TβRII antagonist small molecules; and iv) oneor more TβRII antagonist polynucleotides.

D. Small Molecule Antagonists

In certain aspects, a TβRII antagonist to be used in accordance with themethods and uses disclosed herein is a small molecule (TβRII antagonistsmall molecule) or combination of small molecules. A TβRII antagonistsmall molecule, or combination of small molecules, may inhibit, forexample, one or more TβRII ligands (e.g., TGFβ1, TGFβ2, and TGFβ3),TβRII receptor, TβRII-associated type I receptor (e.g., ALK5),TβRII-associated co-receptor (e.g., betaglycan), and/or downstreamsignaling component (e.g., Smads). In some embodiments, the ability fora TβRII antagonist small molecule, or combination of small molecules, toinhibit signaling (e.g., Smad signaling) is determined in a cell-basedassay including, for example, those described herein. A TβRII antagonistsmall molecule, or combination of small molecules, may be used alone orin combination with one or more additional supportive therapies oractive agents to treat, prevent, or reduce the progression rate and/orseverity of a myeloproliferative disorder (e.g., myelofibrosis,polycythemia vera, and essential thrombocythaemia) and/or a Januskinase-associated disorder (e.g., a JAK2 kinase-associated disorder) orone or more complications of a myeloproliferative disorder and/or aJanus kinase-associated disorder.

In certain aspects, a TβRII antagonist small molecule, or combination ofsmall molecules, inhibits at least TGFβ1 (e.g., inhibition of Smadsignaling). Therefore, in some embodiments, a small molecule inhibitorof TGFβ1 binds to TGFβ1. In some embodiments, a small molecule inhibitorof TGFβ1 inhibits expression (e.g., transcription, translation,secretion, or combinations thereof) of TGFβ1. In some embodiments, asmall molecule inhibitor of TGFβ1 further inhibits one or more of TGFβ2,TGFβ3, TβRII, ALK5, and betaglycan. In some embodiments, a smallmolecule inhibitor of TGFβ1 does not inhibit or does not substantiallyinhibit TGFβ2. In some embodiments, a small molecule inhibitor of TGFβ1further inhibits TGFβ3 but does not inhibit or does not substantiallyinhibit TGFβ2. In certain aspects, a TβRII antagonist small molecule, orcombination of small molecules, inhibits at least TGFβ2 (e.g.,inhibition of Smad signaling). Therefore, in some embodiments, a smallmolecule inhibitor of TGFβ2 binds to TGFβ2. In some embodiments, a smallmolecule inhibitor of TGFβ2 inhibits expression (e.g., transcription,translation, secretion, or combinations thereof) of TGFβ2. In someembodiments, a small molecule inhibitor of TGFβ2 further inhibits one ormore of TGFβ3, TGFβ1, TβRII, ALK5, and betaglycan. In certain aspects, aTβRII antagonist small molecule, or combination of small molecules,inhibits at least TGFβ3 (e.g., inhibition of Smad signaling). Therefore,in some embodiments, a small molecule inhibitor of TGFβ3 binds to TGFβ3.In some embodiments, a small molecule inhibitor of TGFβ3 inhibitsexpression (e.g., transcription, translation, secretion, or combinationsthereof) of TGFβ3. In some embodiments, a small molecule inhibitor ofTGFβ3 further inhibits one or more of TGFβ2, TGFβ1, TβRII, ALK5, andbetaglycan. In some embodiments, a small molecule inhibitor of TGFβ3does not inhibit or does not substantially inhibit TGFβ2. In someembodiments, a small molecule inhibitor of TGFβ3 further inhibits TGFβ1but does not inhibit or does not substantially inhibit TGFβ2. In certainaspects, a TβRII antagonist small molecule, or combination of smallmolecules, inhibits at least TβRII (e.g., inhibition of Smad signaling).Therefore, in some embodiments, a small molecule inhibitor of TβRIIbinds to TβRII. In some embodiments, a small molecule inhibitor of TβRIIinhibits expression (e.g., transcription, translation, secretion, orcombinations thereof) of TβRII. In some embodiments, a small moleculeinhibitor of TβRII further inhibits one or more of TGFβ1, TGFβ2, TGFβ3,ALK5, and betaglycan. In certain aspects, a TβRII antagonist smallmolecule, or combination of small molecules, inhibits TGFβ1 from bindingto TβRII. In certain aspects, a TβRII antagonist small molecule, orcombination of small molecules, inhibits TGFβ2 from binding to TβRII. Incertain aspects, a TβRII antagonist small molecule, or combination ofsmall molecules, inhibits TGFβ3 from binding to TβRII. In certainaspects, a TβRII antagonist small molecule, or combination of smallmolecules, inhibits TGFβ1 and TGFβ3 from binding to TβRII. In certainaspects, a TβRII antagonist small molecule, or combination of smallmolecules, inhibits TGFβ1, TGFβ2, and TGFβ3 from binding to TβRII. Incertain aspects, a TβRII antagonist small molecule, or combination ofsmall molecules, inhibits TGFβ1 from binding to TβRII but does notinhibit or does not substantially inhibit TGFβ2 from binding to TβRII.In certain aspects, a TβRII antagonist small molecule, or combination ofsmall molecules, inhibits TGFβ3 from binding to TβRII but does notinhibit or does not substantially inhibit TGFβ2 from binding to TβRII.In certain aspects, a TβRII antagonist small molecule, or combination ofsmall molecules, inhibits TGFβ1 and TGFβ3 from binding to TβRII but doesnot inhibit or does not substantially inhibit TGFβ2 from binding toTβRII. In certain aspects, a TβRII antagonist small molecule, orcombination of small molecules, inhibits at least ALK5 (e.g., inhibitionof Smad signaling). Therefore, in some embodiments, a small moleculeinhibitor of ALK5 binds to ALK5. In some embodiments, a small moleculeinhibitor of ALK5 inhibits expression (e.g., transcription, translation,secretion, or combinations thereof) of ALK5. In some embodiments, asmall molecule inhibitor of ALK5 further inhibits one or more of TGFβ1,TGFβ2, TGFβ3, TβRII, and betaglycan. In certain aspects, a TβRIIantagonist small molecule, or combination of small molecules, inhibitsTGFβ1 from binding to ALK5. In certain aspects, a TβRII antagonist smallmolecule, or combination of small molecules, inhibits TGFβ2 from bindingto ALK5. In certain aspects, a TβRII antagonist small molecule, orcombination of small molecules, inhibits TGFβ3 from binding to ALK5. Incertain aspects, a TβRII antagonist small molecule, or combination ofsmall molecules, inhibits TGFβ1 and TGFβ3 from binding to ALK5. Incertain aspects, a TβRII antagonist small molecule, or combination ofsmall molecules, inhibits TGFβ1, TGFβ2, and TGFβ3 from binding to ALK5.In certain aspects, a TβRII antagonist small molecule, or combination ofsmall molecules, inhibits TGFβ1 from binding to ALK5 but does notinhibit or does not substantially inhibit TGFβ2 from binding to ALK5. Incertain aspects, a TβRII antagonist small molecule, or combination ofsmall molecules, inhibits TGFβ3 from binding to ALK5 but does notinhibit or does not substantially inhibit TGFβ2 from binding to ALK5. Incertain aspects, a TβRII antagonist small molecule, or combination ofsmall molecules, inhibits TGFβ1 and TGFβ3 from binding to ALK5 but doesnot inhibit or does not substantially inhibit TGFβ2 from binding toALK5. In certain aspects, a TβRII antagonist small molecule, orcombination of small molecules, inhibits at least betaglycan (e.g.,inhibition of Smad signaling). Therefore, in some embodiments, a smallmolecule inhibitor of betaglycan binds to betaglycan. In someembodiments, a small molecule inhibitor of betaglycan inhibitsexpression (e.g., transcription, translation, secretion, or combinationsthereof) of betaglycan. In some embodiments, a small molecule inhibitorof betaglycan further inhibits one or more of TGFβ1, TGFβ2, TGFβ3,TβRII, and ALK5. In certain aspects, a TβRII antagonist small molecule,or combination of small molecules, inhibits TGFβ1 from binding tobetaglycan. In certain aspects, a TβRII antagonist small molecule, orcombination of small molecules, inhibits TGFβ2 from binding tobetaglycan. In certain aspects, a TβRII antagonist small molecule, orcombination of small molecules, inhibits TGFβ3 from binding tobetaglycan. In certain aspects, a TβRII antagonist small molecule, orcombination of small molecules, inhibits TGFβ1 and TGFβ3 from binding tobetaglycan. In certain aspects, a TβRII antagonist small molecule, orcombination of small molecules, inhibits TGFβ1, TGFβ2, and TGFβ3 frombinding to betaglycan. In certain aspects, a TβRII antagonist smallmolecule, or combination of small molecules, inhibits TGFβ1 from bindingto betaglycan but does not inhibit or does not substantially inhibitTGFβ2 from binding to betaglycan. In certain aspects, a TβRII antagonistsmall molecule, or combination of small molecules, inhibits TGFβ3 frombinding to betaglycan but does not inhibit or does not substantiallyinhibit TGFβ2 from binding to betaglycan. In certain aspects, a TβRIIantagonist small molecule, or combination of small molecules, inhibitsTGFβ1 and TGFβ3 from binding to betaglycan but does not inhibit or doesnot substantially inhibit TGFβ2 from binding to betaglycan.

TβRII antagonist small molecules can be direct or indirect inhibitors.For example, a TβRII antagonist small molecule, or combination of smallmolecules, may inhibit the expression (e.g., transcription, translation,cellular secretion, or combinations thereof) of at least one or more ofTβRII, ALK5, betaglycan, TGFβ1, TGFβ2, TGFβ3, and/or one or moredownstream TβRII signaling factors (Smads). Alternatively, a directTβRII antagonist small molecule, or combination of small molecules, maydirectly bind to, for example, one or more of TβRII, ALK5, betaglycan,TGFβ1, TGFβ2, and TGFβ3 or one or more downstream TβRII signalingfactors. Combinations of one or more indirect and one or more directTβRII antagonist small molecule may be used in accordance with themethods disclosed herein.

Binding organic small molecule antagonists of the present disclosure maybe identified and chemically synthesized using known methodology (see,e.g., PCT Publication Nos. WO 00/00823 and WO 00/39585). In general,small molecule antagonists of the disclosure are usually less than about2000 daltons in size, alternatively less than about 1500, 750, 500, 250or 200 daltons in size, wherein such organic small molecules that arecapable of binding, preferably specifically, to a polypeptide asdescribed herein (e.g., TβRII, ALK5, betaglycan, TGFβ1, TGFβ2, andTGFβ3). Such small molecule antagonists may be identified without undueexperimentation using well-known techniques. In this regard, it is notedthat techniques for screening organic small molecule libraries formolecules that are capable of binding to a polypeptide target arewell-known in the art (see, e.g., international patent publication Nos.WO00/00823 and WO00/39585).

Binding organic small molecules of the present disclosure may be, forexample, aldehydes, ketones, oximes, hydrazones, semicarbazones,carbazides, primary amines, secondary amines, tertiary amines,N-substituted hydrazines, hydrazides, alcohols, ethers, thiols,thioethers, disulfides, carboxylic acids, esters, amides, ureas,carbamates, carbonates, ketals, thioketals, acetals, thioacetals, arylhalides, aryl sulfonates, alkyl halides, alkyl sulfonates, aromaticcompounds, heterocyclic compounds, anilines, alkenes, alkynes, diols,amino alcohols, oxazolidines, oxazolines, thiazolidines, thiazolines,enamines, sulfonamides, epoxides, aziridines, isocyanates, sulfonylchlorides, diazo compounds, and acid chlorides.

Any of the TβRII antagonist small molecules disclosed herein can becombined with one or more additional TβRII antagonists to achieve thedesired. For example, a TβRII antagonist small molecule can be used incombination with i) one or more additional TβRII antagonist smallmolecules, ii) one or more TβRII antagonist antibodies disclosed herein;iii) one or more TβRII polypeptides including variants thereof; and/oriv) one or more TβRII antagonist polynucleotides.

E. Antagonist Polynucleotides

In certain aspects, a TβRII antagonist to be used in accordance with themethods and uses disclosed herein is a polynucleotide (TβRII antagonistpolynucleotide) or combination of polynucleotides. A TβRII antagonistpolynucleotide, or combination of polynucleotides, may inhibit, forexample, one or more TβRII ligands (e.g., TGFβ1, TGFβ2, and TGFβ3),TβRII receptor, TβRII-associated type I receptor (e.g., ALK5),TβRII-associated co-receptor (e.g., betaglycan), and/or downstreamsignaling component (e.g., Smads). In some embodiments, the ability fora TβRII antagonist polynucleotide, or combination of polynucleotides, toinhibit signaling (e.g., Smad signaling) is determined in a cell-basedassay including, for example, those described herein. A TβRII antagonistpolynucleotide, or combination of polynucleotide, may be used alone orin combination with one or more additional supportive therapies oractive agents to treat, prevent, or reduce the progression rate and/orseverity of a myeloproliferative disorder (e.g., myelofibrosis,polycythemia vera, and essential thrombocythaemia) and/or a Januskinase-associated disorder (e.g., a JAK2 kinase-associated disorder) orone or more complications of a myeloproliferative disorder and/or aJanus kinase-associated disorder.

In certain aspects, a TβRII antagonist polynucleotide, or combination ofpolynucleotides, inhibits at least TGFβ1 (e.g., inhibition of Smadsignaling). Therefore, in some embodiments, a polynucleotide inhibitorof TGFβ1 binds to TGFβ1. In some embodiments, a polynucleotide inhibitorof TGFβ1 inhibits expression (e.g., transcription, translation,secretion, or combinations thereof) of TGFβ1. In some embodiments, apolynucleotide inhibitor of TGFβ1 further inhibits one or more of TGFβ2,TGFβ3, TβRII, ALK5, and betaglycan. In some embodiments, apolynucleotide inhibitor of TGFβ1 does not inhibit or does notsubstantially inhibit TGFβ2. In some embodiments, a polynucleotideinhibitor of TGFβ1 further inhibits TGFβ3 but does not inhibit or doesnot substantially inhibit TGFβ2. In certain aspects, a TβRII antagonistpolynucleotide, or combination of polynucleotides, inhibits at leastTGFβ2 (e.g., inhibition of Smad signaling). Therefore, in someembodiments, a polynucleotide inhibitor of TGFβ2 binds to TGFβ2. In someembodiments, a polynucleotide inhibitor of TGFβ2 inhibits expression(e.g., transcription, translation, secretion, or combinations thereof)of TGFβ2. In some embodiments, a polynucleotide inhibitor of TGFβ2further inhibits one or more of TGFβ3, TGFβ1, ALK5, and betaglycan. Incertain aspects, a TβRII antagonist polynucleotide, or combination ofpolynucleotides, inhibits at least TGFβ3 (e.g., inhibition of Smadsignaling). Therefore, in some embodiments, a polynucleotide inhibitorof TGFβ3 binds to TGFβ3. In some embodiments, a polynucleotide inhibitorof TGFβ3 inhibits expression (e.g., transcription, translation,secretion, or combinations thereof) of TGFβ3. In some embodiments, apolynucleotide inhibitor of TGFβ3 further inhibits one or more of TGFβ2,TGFβ1, TβRII, ALK5, and betaglycan. In some embodiments, apolynucleotide inhibitor of TGFβ3 does not inhibit or does notsubstantially inhibit TGFβ2. In some embodiments, a polynucleotideinhibitor of TGFβ3 further inhibits TGFβ1 but does not inhibit or doesnot substantially inhibit TGFβ2. In certain aspects, a TβRII antagonistpolynucleotide, or combination of polynucleotides, inhibits at leastTβRII (e.g., inhibition of Smad signaling). Therefore, in someembodiments, a polynucleotide inhibitor of TβRII binds to TβRII. In someembodiments, a polynucleotide inhibitor of TβRII inhibits expression(e.g., transcription, translation, secretion, or combinations thereof)of TβRII. In some embodiments, a polynucleotide inhibitor of TβRIIfurther inhibits one or more of TGFβ1, TGFβ2, TGFβ3, ALK5, andbetaglycan. In some embodiments, a TβRII antagonist polynucleotide, orcombination of polynucleotides, inhibits TGFβ1 from binding to TβRII. Insome embodiments a TβRII antagonist polynucleotide, or combination ofpolynucleotides, inhibits TGFβ2 from binding to TβRII. In someembodiments, a TβRII antagonist polynucleotide, or combination ofpolynucleotides, inhibits TGFβ3 from binding to TβRII. In someembodiments, a TβRII antagonist polynucleotide, or combination ofpolynucleotides, inhibits TGFβ1 and TGFβ3 from binding to TβRII. In someembodiments, a TβRII antagonist polynucleotide, or combination ofpolynucleotides, inhibits TGFβ1, TGFβ2, and TGFβ3 from binding to TβRII.In some embodiments, a TβRII antagonist polynucleotide, or combinationof polynucleotides, inhibits TGFβ1 from binding to TβRII but does notinhibit or does not substantially inhibit TGFβ2 from binding to TβRII.In some embodiments, a TβRII antagonist polynucleotide, or combinationof polynucleotides, inhibits TGFβ3 from binding to TβRII but does notinhibit or does not substantially inhibit TGFβ2 from binding to TβRII.In some embodiments, a TβRII antagonist polynucleotide, or combinationof polynucleotides, inhibits TGFβ1 and TGFβ3 from binding to TβRII butdoes not inhibit or does not substantially inhibit TGFβ2 from binding toTβRII. In certain aspects, a TβRII antagonist polynucleotide, orcombination of polynucleotides, inhibits at least ALK5 (e.g., inhibitionof Smad signaling). Therefore, in some embodiments, a polynucleotideinhibitor of ALK5 binds to ALK5. In some embodiments, a polynucleotideinhibitor of ALK5 inhibits expression (e.g., transcription, translation,secretion, or combinations thereof) of ALK5. In some embodiments, apolynucleotide inhibitor of ALK5 further inhibits one or more of TGFβ1,TGFβ2, TGFβ3, TβRII, and betaglycan. In some embodiments, a TβRIIantagonist polynucleotide, or combination of polynucleotides, inhibitsTGFβ1 from binding to ALK5. In some embodiments, a TβRII antagonistpolynucleotide, or combination of polynucleotides, inhibits TGFβ2 frombinding to ALK5. In some embodiments, a TβRII antagonist polynucleotide,or combination of polynucleotides, inhibits TGFβ3 from binding to ALK5.In some embodiments, a TβRII antagonist polynucleotide, or combinationof polynucleotides, inhibits TGFβ1 and TGFβ3 from binding to ALK5. Insome embodiments, a TβRII antagonist polynucleotide, or combination ofpolynucleotides, inhibits TGFβ1, TGFβ2, and TGFβ3 from binding to ALK5.In some embodiments, a TβRII antagonist polynucleotide, or combinationof polynucleotides, inhibits TGFβ1 from binding to ALK5 but does notinhibit or does not substantially inhibit TGFβ2 from binding to ALK5. Insome embodiments, a TβRII antagonist polynucleotide, or combination ofpolynucleotides, inhibits TGFβ3 from binding to ALK5 but does notinhibit or does not substantially inhibit TGFβ2 from binding to ALK5. Insome embodiments, a TβRII antagonist polynucleotide, or combination ofpolynucleotides, inhibits TGFβ1 and TGFβ3 from binding to ALK5 but doesnot inhibit or does not substantially inhibit TGFβ2 from binding toALK5. In certain aspects, a TβRII antagonist polynucleotide, orcombination of polynucleotides, inhibits at least betaglycan (e.g.,inhibition of Smad signaling). Therefore, in some embodiments, apolynucleotide inhibitor of betaglycan binds to betaglycan. In someembodiments, a polynucleotide inhibitor of betaglycan inhibitsexpression (e.g., transcription, translation, secretion, or combinationsthereof) of betaglycan. In some embodiments, a polynucleotide inhibitorof betaglycan further inhibits one or more of TGFβ1, TGFβ2, TGFβ3,TβRII, and ALK5. In some embodiments, a TβRII antagonist polynucleotide,or combination of polynucleotides, inhibits TGFβ1 from binding tobetaglycan. In some embodiments, a TβRII antagonist polynucleotide, orcombination of polynucleotides, inhibits TGFβ2 from binding tobetaglycan. In some embodiments, a TβRII antagonist polynucleotide, orcombination of polynucleotides, inhibits TGFβ3 from binding tobetaglycan. In some embodiments, a TβRII antagonist polynucleotide, orcombination of polynucleotides, inhibits TGFβ1 and TGFβ3 from binding tobetaglycan. In some embodiments, a TβRII antagonist polynucleotide, orcombination of polynucleotides, inhibits TGFβ1, TGFβ2, and TGFβ3 frombinding to betaglycan. In some embodiments, a TβRII antagonistpolynucleotide, or combination of polynucleotides, inhibits TGFβ1 frombinding to betaglycan but does not inhibit or does not substantiallyinhibit TGFβ2 from binding to betaglycan. In some embodiments, a TβRIIantagonist polynucleotide, or combination of polynucleotides, inhibitsTGFβ3 from binding to betaglycan but does not inhibit or does notsubstantially inhibit TGFβ2 from binding to betaglycan. In someembodiments, a TβRII antagonist polynucleotide, or combination ofpolynucleotides, inhibits TGFβ1 and TGFβ3 from binding to betaglycan butdoes not inhibit or does not substantially inhibit TGFβ2 from binding tobetaglycan.

The polynucleotide antagonists of the present disclosure may be anantisense nucleic acid, an RNAi molecule [e.g., small interfering RNA(siRNA), small-hairpin RNA (shRNA), microRNA (miRNA)], an aptamer and/ora ribozyme. The nucleic acid and amino acid sequences of human TβRII,ALK5, betaglycan, TGFβ1, TGFβ2, and TGFβ3 are known in the art and thuspolynucleotide antagonists for use in accordance with methods of thepresent disclosure may be routinely made by the skilled artisan based onthe knowledge in the art and teachings provided herein.

For example, antisense technology can be used to control gene expressionthrough antisense DNA or RNA, or through triple-helix formation.Antisense techniques are discussed, for example, in Okano (1991) J.Neurochem. 56:560; Oligodeoxynucleotides as Antisense Inhibitors of GeneExpression, CRC Press, Boca Raton, Fla. (1988). Triple helix formationis discussed in, for instance, Cooney et al. (1988) Science 241:456; andDervan et al., (1991)Science 251:1300. The methods are based on bindingof a polynucleotide to a complementary DNA or RNA. In some embodiments,the antisense nucleic acids comprise a single-stranded RNA or DNAsequence that is complementary to at least a portion of an RNAtranscript of a desired gene. However, absolute complementarity,although preferred, is not required.

A sequence “complementary to at least a portion of an RNA,” referred toherein, means a sequence having sufficient complementarity to be able tohybridize with the RNA, forming a stable duplex; in the case ofdouble-stranded antisense nucleic acids of a gene disclosed herein, asingle strand of the duplex DNA may thus be tested, or triplex formationmay be assayed. The ability to hybridize will depend on both the degreeof complementarity and the length of the antisense nucleic acid.Generally, the larger the hybridizing nucleic acid, the more basemismatches with an RNA it may contain and still form a stable duplex (ortriplex as the case may be). One skilled in the art can ascertain atolerable degree of mismatch by use of standard procedures to determinethe melting point of the hybridized complex.

Polynucleotides that are complementary to the 5′ end of the message, forexample, the 5′-untranslated sequence up to and including the AUGinitiation codon, should work most efficiently at inhibitingtranslation. However, sequences complementary to the 3′-untranslatedsequences of mRNAs have been shown to be effective at inhibitingtranslation of mRNAs as well [see, e.g., Wagner, R., (1994) Nature372:333-335]. Thus, oligonucleotides complementary to either the 5′- or3′-untranslated, noncoding regions of a gene of the disclosure, could beused in an antisense approach to inhibit translation of an endogenousmRNA. Polynucleotides complementary to the 5′-untranslated region of themRNA should include the complement of the AUG start codon. Antisensepolynucleotides complementary to mRNA coding regions are less efficientinhibitors of translation but could be used in accordance with themethods of the present disclosure. Whether designed to hybridize to the5′-untranslated, 3′-untranslated, or coding regions of an mRNA of thedisclosure, antisense nucleic acids should be at least six nucleotidesin length, and are preferably oligonucleotides ranging from 6 to about50 nucleotides in length. In specific aspects, the oligonucleotide is atleast 10 nucleotides, at least 17 nucleotides, at least 25 nucleotides,or at least 50 nucleotides.

In one embodiment, the antisense nucleic acid of the present disclosureis produced intracellularly by transcription from an exogenous sequence.For example, a vector or a portion thereof, is transcribed, producing anantisense nucleic acid (RNA) of a gene of the disclosure. Such a vectorwould contain a sequence encoding the desired antisense nucleic acid.Such a vector can remain episomal or become chromosomally integrated, aslong as it can be transcribed to produce the desired antisense RNA. Suchvectors can be constructed by recombinant DNA technology methodsstandard in the art. Vectors can be plasmid, viral, or others known inthe art, used for replication and expression in vertebrate cells.Expression of the sequence encoding desired genes of the instantdisclosure, or fragments thereof, can be by any promoter known in theart to act in vertebrate, preferably human cells. Such promoters can beinducible or constitutive. Such promoters include, but are not limitedto, the 5V40 early promoter region [see, e.g., Benoist and Chambon(1981) Nature 29:304-310], the promoter contained in the 3′ longterminal repeat of Rous sarcoma virus [see, e.g., Yamamoto et al. (1980)Cell 22:787-797], the herpes thymidine promoter [see, e.g., Wagner etal. (1981) Proc. Natl. Acad. Sci. U.S.A. 78:1441-1445], and theregulatory sequences of the metallothionein gene [see, e.g., Brinster,et al. (1982) Nature 296:39-42].

In some embodiments, the polynucleotide antagonists are interfering RNAor RNAi molecules that target the expression of one or more genes. RNAirefers to the expression of an RNA which interferes with the expressionof the targeted mRNA. Specifically, RNAi silences a targeted gene viainteracting with the specific mRNA through a siRNA (small interferingRNA). The ds RNA complex is then targeted for degradation by the cell.An siRNA molecule is a double-stranded RNA duplex of 10 to 50nucleotides in length, which interferes with the expression of a targetgene which is sufficiently complementary (e.g. at least 80% identity tothe gene). In some embodiments, the siRNA molecule comprises anucleotide sequence that is at least 85, 90, 95, 96, 97, 98, 99, or 100%identical to the nucleotide sequence of the target gene.

Additional RNAi molecules include short-hairpin RNA (shRNA); alsoshort-interfering hairpin and microRNA (miRNA). The shRNA moleculecontains sense and antisense sequences from a target gene connected by aloop. The shRNA is transported from the nucleus into the cytoplasm, andit is degraded along with the mRNA. Pol III or U6 promoters can be usedto express RNAs for RNAi. Paddison et al. [Genes & Dev. (2002)16:948-958, 2002] have used small RNA molecules folded into hairpins asa means to effect RNAi. Accordingly, such short hairpin RNA (shRNA)molecules are also advantageously used in the methods described herein.The length of the stem and loop of functional shRNAs varies; stemlengths can range anywhere from about 25 to about 30 nt, and loop sizecan range between 4 to about 25 nt without affecting silencing activity.While not wishing to be bound by any particular theory, it is believedthat these shRNAs resemble the double-stranded RNA (dsRNA) products ofthe DICER RNase and, in any event, have the same capacity for inhibitingexpression of a specific gene. The shRNA can be expressed from alentiviral vector. An miRNA is a single-stranded RNA of about 10 to 70nucleotides in length that are initially transcribed as pre-miRNAcharacterized by a “stem-loop” structure and which are subsequentlyprocessed into mature miRNA after further processing through the RISC.

Molecules that mediate RNAi, including without limitation siRNA, can beproduced in vitro by chemical synthesis (Hohjoh, FEBS Lett 521:195-199,2002), hydrolysis of dsRNA (Yang et al., Proc Natl Acad Sci USA99:9942-9947, 2002), by in vitro transcription with T7 RNA polymerase(Donzeet et al., Nucleic Acids Res 30:e46, 2002; Yu et al., Proc NatlAcad Sci USA 99:6047-6052, 2002), and by hydrolysis of double-strandedRNA using a nuclease such as E. coli RNase III (Yang et al., Proc NatlAcad Sci USA 99:9942-9947, 2002).

According to another aspect, the disclosure provides polynucleotideantagonists including but not limited to, a decoy DNA, a double-strandedDNA, a single-stranded DNA, a complexed DNA, an encapsulated DNA, aviral DNA, a plasmid DNA, a naked RNA, an encapsulated RNA, a viral RNA,a double-stranded RNA, a molecule capable of generating RNAinterference, or combinations thereof.

In some embodiments, the polynucleotide antagonists of the disclosureare aptamers. Aptamers are nucleic acid molecules, includingdouble-stranded DNA and single-stranded RNA molecules, which bind to andform tertiary structures that specifically bind to a target molecule,such as a TβRII, TGFβ1, TGFβ2, and TGFβ3 polypeptide. The generation andtherapeutic use of aptamers are well established in the art. See, e.g.,U.S. Pat. No. 5,475,096. Additional information on aptamers can be foundin U.S. Patent Application Publication No. 20060148748. Nucleic acidaptamers are selected using methods known in the art, for example viathe Systematic Evolution of Ligands by Exponential Enrichment (SELEX)process. SELEX is a method for the in vitro evolution of nucleic acidmolecules with highly specific binding to target molecules as describedin, e.g., U.S. Pat. Nos. 5,475,096, 5,580,737, 5,567,588, 5,707,796,5,763,177, 6,011,577, and 6,699,843. Another screening method toidentify aptamers is described in U.S. Pat. No. 5,270,163. The SELEXprocess is based on the capacity of nucleic acids for forming a varietyof two- and three-dimensional structures, as well as the chemicalversatility available within the nucleotide monomers to act as ligands(form specific binding pairs) with virtually any chemical compound,whether monomeric or polymeric, including other nucleic acid moleculesand polypeptides. Molecules of any size or composition can serve astargets. The SELEX method involves selection from a mixture of candidateoligonucleotides and step-wise iterations of binding, partitioning andamplification, using the same general selection scheme, to achievedesired binding affinity and selectivity. Starting from a mixture ofnucleic acids, which can comprise a segment of randomized sequence, theSELEX method includes steps of contacting the mixture with the targetunder conditions favorable for binding; partitioning unbound nucleicacids from those nucleic acids which have bound specifically to targetmolecules; dissociating the nucleic acid-target complexes; amplifyingthe nucleic acids dissociated from the nucleic acid-target complexes toyield a ligand enriched mixture of nucleic acids. The steps of binding,partitioning, dissociating and amplifying are repeated through as manycycles as desired to yield highly specific high affinity nucleic acidligands to the target molecule.

Typically, such binding molecules are separately administered to theanimal [see, e.g., O'Connor (1991) J. Neurochem. 56:560], but suchbinding molecules can also be expressed in vivo from polynucleotidestaken up by a host cell and expressed in vivo [see, e.g.,Oligodeoxynucleotides as Antisense Inhibitors of Gene Expression, CRCPress, Boca Raton, Fla. (1988)].

Any of the TβRII antagonist polynucleotides can be combined with one ormore additional TβRII antagonists to achieve the desired effect. Forexample, a TβRII antagonist polynucleotide can be used in combinationwith i) one or more additional TβRII antagonist polynucleotides, ii) oneor more TβRII polypeptides including variants thereof; iii) one or moreTβRII antagonist antibodies; and/or iv) one or more TβRII antagonistsmall molecules.

5. Screening Assays

In certain aspects, the present invention relates to the use of TβRIIpolypeptides (e.g., soluble TβRII polypeptides) to identify compounds(agents) which are agonist or antagonists of the TGFβ-TβRII signalingpathway. Compounds identified through this screening can be tested toassess their ability to modulate TGFβ signaling activity in vitro.Optionally, these compounds can further be tested in animal models toassess their ability to modulate tissue growth in vivo.

There are numerous approaches to screening for therapeutic agents formodulating tissue growth by targeting TGFβ and TβRII polypeptides. Incertain embodiments, high-throughput screening of compounds can becarried out to identify agents that perturb TGFβ or TβRII-mediated cellsignaling. In certain embodiments, the assay is carried out to screenand identify compounds that specifically inhibit or reduce binding of aTβRII polypeptide to TGFβ. Alternatively, the assay can be used toidentify compounds that enhance binding of a TβRII polypeptide to TGFβ.In a further embodiment, the compounds can be identified by theirability to interact with a TGFβ or TβRII polypeptide.

A variety of assay formats will suffice and, in light of the presentdisclosure, those not expressly described herein will nevertheless becomprehended by one of ordinary skill in the art. As described herein,the test compounds (agents) of the invention may be created by anycombinatorial chemical method. Alternatively, the subject compounds maybe naturally occurring biomolecules synthesized in vivo or in vitro.Compounds (agents) to be tested for their ability to act as modulatorsof tissue growth can be produced, for example, by bacteria, yeast,plants or other organisms (e.g., natural products), produced chemically(e.g., small molecules, including peptidomimetics), or producedrecombinantly. Test compounds contemplated by the present inventioninclude non-peptidyl organic molecules, peptides, polypeptides,peptidomimetics, sugars, hormones, and nucleic acid molecules. In aspecific embodiment, the test agent is a small organic molecule having amolecular weight of less than about 2,000 daltons.

The test compounds of the invention can be provided as single, discreteentities, or provided in libraries of greater complexity, such as madeby combinatorial chemistry. These libraries can comprise, for example,alcohols, alkyl halides, amines, amides, esters, aldehydes, ethers andother classes of organic compounds. Presentation of test compounds tothe test system can be in either an isolated form or as mixtures ofcompounds, especially in initial screening steps. Optionally, thecompounds may be optionally derivatized with other compounds and havederivatizing groups that facilitate isolation of the compounds.Non-limiting examples of derivatizing groups include biotin,fluorescein, digoxygenin, green fluorescent protein, isotopes,polyhistidine, magnetic beads, glutathione S transferase (GST),photoactivatible crosslinkers or any combinations thereof.

In many drug screening programs which test libraries of compounds andnatural extracts, high throughput assays are desirable in order tomaximize the number of compounds surveyed in a given period of time.Assays which are performed in cell-free systems, such as may be derivedwith purified or semi-purified proteins, are often preferred as“primary” screens in that they can be generated to permit rapiddevelopment and relatively easy detection of an alteration in amolecular target which is mediated by a test compound. Moreover, theeffects of cellular toxicity or bioavailability of the test compound canbe generally ignored in the in vitro system, the assay instead beingfocused primarily on the effect of the drug on the molecular target asmay be manifest in an alteration of binding affinity between a TβRIIpolypeptide and TGFβ.

Merely to illustrate, in an exemplary screening assay of the presentinvention, the compound of interest is contacted with an isolated andpurified TβRII polypeptide which is ordinarily capable of binding toTGFβ. To the mixture of the compound and TβRII polypeptide is then addeda composition containing a TβRII ligand. Detection and quantification ofTβRII/TGFβ complexes provides a means for determining the compound'sefficacy at inhibiting (or potentiating) complex formation between theTβRII polypeptide and TGFβ. The efficacy of the compound can be assessedby generating dose response curves from data obtained using variousconcentrations of the test compound. Moreover, a control assay can alsobe performed to provide a baseline for comparison. For example, in acontrol assay, isolated and a purified TGFβ is added to a compositioncontaining the TβRII polypeptide, and the formation of TβRII/TGFβcomplex is quantitated in the absence of the test compound. It will beunderstood that, in general, the order in which the reactants may beadmixed can be varied, and can be admixed simultaneously. Moreover, inplace of purified proteins, cellular extracts and lysates may be used torender a suitable cell-free assay system.

Complex formation between the TβRII polypeptide and TGFβ may be detectedby a variety of techniques. For instance, modulation of the formation ofcomplexes can be quantitated using, for example, detectably labeledproteins such as radiolabeled (e.g., ³²P, ³⁵S, ¹⁴C or ³H), fluorescentlylabeled (e.g., FITC), or enzymatically labeled TβRII polypeptide orTGFβ, by immunoassay, or by chromatographic detection.

In certain embodiments, the present invention contemplates the use offluorescence polarization assays and fluorescence resonance energytransfer (FRET) assays in measuring, either directly or indirectly, thedegree of interaction between a TβRII polypeptide and its bindingprotein. Further, other modes of detection, such as those based onoptical waveguides (PCT Publication WO 96/26432 and U.S. Pat. No.5,677,196), surface plasmon resonance (SPR), surface charge sensors, andsurface force sensors, are compatible with many embodiments of theinvention.

Moreover, the present invention contemplates the use of an interactiontrap assay, also known as the “two hybrid assay,” for identifying agentsthat disrupt or potentiate interaction between a TβRII polypeptide andits binding protein. See for example, U.S. Pat. No. 5,283,317; Zervos etal. (1993) Cell 72:223-232; Madura et al. (1993) J Biol Chem268:12046-12054; Bartel et al. (1993) Biotechniques 14:920-924; andIwabuchi et al. (1993) Oncogene 8:1693-1696). In a specific embodiment,the present invention contemplates the use of reverse two hybrid systemsto identify compounds (e.g., small molecules or peptides) thatdissociate interactions between a TβRII polypeptide and its bindingprotein. See for example, Vidal and Legrain, (1999) Nucleic Acids Res27:919-29; Vidal and Legrain, (1999) Trends Biotechnol 17:374-81; andU.S. Pat. Nos. 5,525,490; 5,955,280; and 5,965,368.

In certain embodiments, the subject compounds are identified by theirability to interact with a TβRII or TGFβ polypeptide of the invention.The interaction between the compound and the TβRII or TGFβ polypeptidemay be covalent or non-covalent. For example, such interaction can beidentified at the protein level using in vitro biochemical methods,including photo-crosslinking, radiolabeled ligand binding, and affinitychromatography (Jakoby W B et al., 1974, Methods in Enzymology 46: 1).In certain cases, the compounds may be screened in a mechanism basedassay, such as an assay to detect compounds which bind to a TGFβ orTβRII polypeptide. This may include a solid-phase or fluid-phase bindingevent. Alternatively, the gene encoding a TGFβ or TβRII polypeptide canbe transfected with a reporter system (e.g., β-galactosidase,luciferase, or green fluorescent protein) into a cell and screenedagainst the library preferably by a high-throughput screening or withindividual members of the library. Other mechanism-based binding assaysmay be used, for example, binding assays which detect changes in freeenergy. Binding assays can be performed with the target fixed to a well,bead or chip or captured by an immobilized antibody or resolved bycapillary electrophoresis. The bound compounds may be detected usuallyusing colorimetric or fluorescence or surface plasmon resonance.

In certain aspects, the present invention provides methods and agentsfor modulating (stimulating or inhibiting) TGFβ-mediated cell signaling.Therefore, any compound identified can be tested in whole cells ortissues, in vitro or in vivo, to confirm their ability to modulate TGFβsignaling. Various methods known in the art can be utilized for thispurpose.

6. Exemplary Therapeutic Uses

The myeloproliferative neoplasms (MPNs) arise from aberranthematopoietic stem cell proliferation and include myelofibrosis (PMF),polycythemia vera (PV) and essential thrombocythemia (ET) [Mesa, R. A.(2013 Leuk Lymphoma 54(2):242-251]. ET and PV are capable of evolvinginto myelofibrosis (post ET-related myelofibrosis and post PV-relatedmyelofibrosis, respectively) [Thiele et al. (2008) WHO Classification ofTumours of Haematopoietic and Lymphoid Tissues. IARC Lyon: World HealthOrganization, 44-7; and Cervantes et al. (2009) Blood 113(13):2895-901].Despite certain idiosyncratic features, these myelofibrotic diseaseshave remarkable phenotypic and clinical commonalities, such as theirproclivity to develop thrombotic and hemorrhagic complications and toprogress to acute myeloid leukemia [Spivak, J. L. (2002) Blood100:4272-4290; Finazzi et al. (2007) Blood 190:5104-5111; and Passamnotiet al. (2010) Blood 115:1703-1708]. Prior to the Food and DrugAdministration (FDA) approval of ruxolitinib (e.g., Jakafi), there wereno approved treatments for the treatment of MF other than hematopoieticstem cell transplant (HSCT). Improved understanding of the diseasebiology has led to an increase in clinical trials evaluating potentialnew classes of therapeutics. However, a significant unmet need stillremain for the treatment of myeloproliferative disorders.

In certain aspects, the present disclosure provides methods fortreating, preventing, or reducing the progression rate and/or severityof a myeloproliferative disorder (e.g., BCR-ABL-negativemyeloproliferative neoplasms including primary myelofibrosis,polycythemia vera, masked polycythemia, essential thrombocythemia,post-polycythemia vera myelofibrosis, and post-essentialthrombocythaemia myelofibrosis) or one or more complications of amyeloproliferative disorder (e.g., fibrosis, splenomegaly, inflammation,anemia, and extramedullary hematopoiesis) comprising administering to apatient in need thereof an effective amount of one or more TβRIIantagonists (e.g., a TβRII polypeptide comprising, consisting essentialof, or consisting of the amino acid sequence that is at least 85%, 90%,91%, 92%, 93%, 94% 95%, 96%, 97%, 98%, 99%, or 100% identical to theamino acid sequence of any one of SEQ ID NOs: 5-17, 25, 27, 29, 31, 33,35, 37, 39, 41, 43, 47-49, 53-62, 101, and 103-105), optionally incombination with one or more additional supportive therapies and/oractive agents for treating a myeloproliferative disorder (e.g., a Januskinase inhibitor such as ruxolitinib).

In certain aspects, the present disclosure provides methods of treating,preventing, or reducing the progression rate and/or severity of a Januskinase-associated disorder (e.g., a JAK2 kinase-associated disorder) orone or more complications of a Janus kinase-associated disordercomprising administering to a patient in need thereof an effectiveamount of one or more TβRII antagonists (e.g., a TβRII polypeptidecomprising, consisting essential of, or consisting of the amino acidsequence that is at least 85%, 90%, 91%, 92%, 93%, 94% 95%, 96%, 97%,98%, 99%, or 100% identical to the amino acid sequence of any one of SEQID NOs: 5-17, 25, 27, 29, 31, 33, 35, 37, 39, 41, 43, 47-49, 53-62, 101,and 103-105), optionally in combination with one or more additionalsupportive therapies and/or active agents for treating a Januskinase-associated disorder (e.g., a Janus kinase inhibitor such asruxolitinib). Janus kinase-associated disorders that may be treated orprevented by the methods of the disclosure include, for example,myeloproliferative disorders (e.g. primary myelofibrosis, polycythemiavera, masked polycythemia vera essential thrombocythaemia,post-polycythemia vera myelofibrosis, post-essential thrombocythaemiamyelofibrosis, and CML), other hematological disorders associated with aJanus kinase-associated disorder, and other clonal disorders associatedwith a Janus kinase-associated disorder as well as complications arisingtherefrom.

As used herein, a therapeutic that “prevents” a disorder or conditionrefers to a compound that, in a statistical sample, reduces theoccurrence of the disorder or condition in the treated sample relativeto an untreated control sample, or delays the onset or reduces theseverity of one or more symptoms of the disorder or condition relativeto the untreated control sample.

The term “treating” as used herein includes amelioration or eliminationof the condition once it has been established. In either case,prevention or treatment may be discerned in the diagnosis provided by aphysician or other health care provider and the intended result ofadministration of the therapeutic agent.

In general, treatment or prevention of a disease or condition asdescribed in the present disclosure is achieved by administering a TβRIIantagonist in an effective amount. An effective amount of an agentrefers to an amount effective, at dosages and for periods of timenecessary, to achieve the desired therapeutic or prophylactic result. Atherapeutically effective amount of an agent of the present disclosuremay vary according to factors such as the disease state, age, sex, andweight of the individual, and the ability of the agent to elicit adesired response in the individual. A prophylactically effective amountrefers to an amount effective, at dosages and for periods of timenecessary, to achieve the desired prophylactic result.

Myelofibrosis is a clonal neoplastic disorder of hematopoiesis,generally characterized by progressive bone marrow fibrosis resulting inincreasingly ineffective hematopoiesis, extramedullary hematopoiesis, avariety of inflammatory complications, and shortened survival[Mascarenhas et al. (2012) Curr Med Chem 19:4399-4413; and Vannucchi etal. (2011) Hematol Am Soc Hematol Educ Prog 2011:222-230]. It is one ofthe myeloproliferative disorders of the bone marrow in which excesscells are produced. Production of cytokines such fibroblast growthfactor by the abnormal hematopoietic cell clone leads to replacement ofthe hematopoietic tissue of the bone marrow by connective tissue viacollagen fibrosis. The decrease in hematopoietic tissue impairs thepatient's ability to generate new blood cells, resulting in progressivepancytopenia, a shortage of all blood types. However, the proliferationand fibroblasts and deposition of collagen is a secondary phenomenon,and the fibroblasts themselves are not part of the abnormal cell clone.As a result of progressive scarring, or fibrosis, of the bone marrow,patients develop extramedullary hematopoiesis as the haemopoetic cellsare forced to migrate to other areas, particularly the liver and spleen.This causes an enlargement of these organs. In the liver, the conditionis call hepatomegaly. Enlargement of the spleen is called splenomegaly,which also contributes pancytopenia, particularly thrombocytopenia andanemia. There are also reports of extramedullary hematopoiesis occurringin the lungs and lymph nodes. Another complication of extramedullaryhematopoiesis is poikilocytosis, of the presence of abnormally shapedred blood cells. Common clinical manifestations of myelofibrosis includeprogressive hepatosplenomegaly, abnormal blood counts, and debilitatingsymptoms such as fatigue, weight loss, night sweats, fever, pruritus,bone pain, early satiety, abdominal pain or discomfort, arthralgias,myalgias, parasthesias, cachexia, splenic infarct and bleeding. Untilrecently, the only treatment with a clearly demonstrated impact ondisease progression has been allogeneic hematopoietic stem celltransplantation alloHSCT, but treatment-related mortality is high andonly a minority of patients qualify for this intensive therapy [Gupta etal. (2012) Blood 120: 1367-1379].

In certain aspects, a TβRII antagonist may be used, alone or incombination with one or more supportive therapies or active agents, totreat, prevent, or reduce the progression rate and/or severity ofmyelofibrosis (e.g., primary myelofibrosis, post-polycythemia veramyelofibrosis, and post-essential thrombocythemia myelofibrosis). Inparticular, TβRII antagonists may be used, alone or in combination withone or more supportive therapies or active agents, to treat, prevent, orreduce the progression rate and/or severity of one or more complicationsof myelofibrosis including, for example, ineffective hematopoiesis,anemia, inflammation, fibrosis (e.g., bone marrow fibrosis, spleenfibrosis, and liver fibrosis), pancytopenia, neutropenia, elevatedcytokines, coagulopathy, an inflammatory complication, IL-6-mediatedinflammation or inflammatory complication, thrombocytopenia,extramedullary hematopoiesis (e.g., splenic extramedullaryhematopoiesis, hepatic extramedullary hematopoiesis, pulmonaryextramedullary hematopoiesis, and lymphatic extramedullaryhematopoiesis), hepatomegaly, splenomegaly, osteosclerosis,osteomyelofibrosis, poikilocytosis, fatigue, weight loss, night sweats,fever, pruritus, bone pain, early satiety, abdominal pain or discomfort,arthralgias, myalgias, parasthesias, cachexia, splenic infarct, andbleeding.

Current diagnosis of primary myelofibrosis (PMF) is based on WorldHealth Organization (WHO)-criteria and involves a composite assessmentof clinical and laboratory features [Tefferi A et al. (2007) Blood.110:1092-1097]. There are three WHO diagnostic primary criteria: 1)megakaryocyte proliferation and atypia (small to large megakaryocyteswith aberrant nuclear/cytoplasmic ratio and hyperchromatic andirregularly folded nuclei and dense clustering) accompanied by eitherreticulin and/or collagen fibrosis or, in the absence of reticulinfibrosis, the megakaryocyte changes must be accompanied by increasedmarrow cellularity, granulocytic proliferation, and often decreasederythropoiesis (i.e., pre-fibrotic primary myelofibrosis), 2) notmeeting WHO criteria for chronic myelogenous leukemia, polycythemiavera, myelodysplastic syndrome, or other myeloid neoplasm, and 3)demonstration of JAK2V617F or other clonal marker or no evidence ofreactive bone marrow fibrosis. In addition, there are four WHOdiagnostic minor criteria: 1) leukoerythroblastosis, 2) increased serumLDH levels, 3) anemia, and 4) palpable splenomegaly. Peripheral bloodleukoerythroblastosis (i.e., presence of nucleated red cells, immaturegranulocytes, and dacryocytes) is a typical but not invariable featureof PMF; prefibrotic PMF might not display overt leukoerythroblastosis[Kvasnicka et al. (2010) Am J Hematol. 85:62-69]. Bone marrow fibrosisin PMF is usually associated with JAK2V617F or mutant CALR, or MPL,trisomy 9, or del(13q) [Hussein et al. (2009) Eur J Haematol.82:329-338]. The presence of these genetic markers, therefore, stronglysupports a diagnosis of PMF, in the presence of a myeloid neoplasmassociated with bone marrow fibrosis. In certain aspects, the disclosurerelates to methods and uses of TβRII antagonists to treat, prevent, orreduce the progression rate and/or severity of primary myelofibrosis,particularly treating, preventing, or reducing the progression rateand/or severity of one or more complications of primary myelofibrosis.

Current diagnosis of post-polycythemia vera myelofibrosis (post-PV MF)and post-essential thrombocythemia myelofibrosis (post-ET MF) are basedon the criteria published by the International Working Group for MPNResearch and Treatment (IWG-MRT) [Barosi G et al. (2008) Leukemia.22:437-438]. There are two IWG-MRT primary criteria for post-PV MF: 1)documentation of previous diagnosis of polycythemia vera as defined bythe WHO criteria, and 2) bone marrow fibrosis grade 2-3 (on 0-3 scale)or grade 3-4 (on 0-4 scale). Grade 2-3 according to the Europeanclassification: diffuse, often coarse fiber network with no evidence ofcollagenization (negative trichrome stain) or diffuse, coarse fibernetwork with areas of collagenization (positive trichrome stain) [Thieleet al. (2005) Haematologica. 90:1128-1132]. Grade 3-4 according to thestandard classification: diffuse and dense increase in reticulin withextensive intersections, occasionally with only focal bundles ofcollagen and/or focal osteosclerosis or diffuse and dense increase inreticulin with extensive intersections with coarse bundles of collagen,often associated with significant osteosclerosis [Manoharan et al.(1979) Br J Haematol 43:185-190]. In addition, there are four IWG-MRTdiagnostic secondary criteria, of which two must be detected in apatient along with the IWG-MRT primary criteria for a post-PV MFdiagnosis: 1) anemia or sustained loss of requirement for phlebotomy inthe absence of cytoreductive therapy, 2) a leukoerythroblasticperipheral blood picture, 3) increasing splenomegaly defined as eitheran increase in palpable splenomegaly of ≧5 cm or the appearance of anewly palpable splenomegaly, 4) development of ≧1 of threeconstitutional symptoms: >10% weight loss in six months, night sweats,unexplained fever. There are two IWG-MRT primary criteria for post-ETMF: 1) documentation of a previous diagnosis of polycythemia vera asdefined by the WHO criteria, 2) bone marrow fibrosis grade 2-3 (on 0-3scale) or grade 3-4 (on 0-4 scale). In addition, there are five IWG-MRTdiagnostic secondary criteria, of which two must be detected in apatient along with the IWG-MRT primary criteria for a post-ET MFdiagnosis: 1) anemia and a ≧2 g/dL decrease from baseline hemoglobinlevels, 2) a leukoerythroblastic peripheral blood picture, 3) increasingsplenomegaly defined as either an increase in palpable splenomegaly of≧5 cm or the appearance of a newly palpable splenomegaly, 4) increasedlactate dehydrogenase, and 5) development of ≧1 of three constitutionalsymptoms: >10% weight loss in six months, night sweats, unexplainedfever. In certain aspects, the disclosure relates to methods and uses ofTβRII antagonists to treat, prevent, or reduce the progression rateand/or severity of post-polycythemia vera myelofibrosis, particularlytreating, preventing, or reducing the progression rate and/or severityof one or more complications of post-polycythemia vera myelofibrosis. Incertain aspects, the disclosure relates to methods and uses of TβRIIantagonists to treat, prevent, or reduce the progression rate and/orseverity of post-essential thrombocythemia myelofibrosis, particularlytreating, preventing, or reducing the progression rate and/or severityof one or more complications of post-essential thrombocythemiamyelofibrosis.

Robust prognostic modeling in myelofibrosis started with the developmentof the International Prognostic Scoring System (IPSS) in 2009 [CervantesF et al. (2009) Blood 113:2895-2901]. The IPSS for myelofibrosis isapplicable to patients being evaluated at time of initial diagnosis anduses five independent predictors of inferior survival: age ≧65 years,hemoglobin <10 g/dL, leukocyte count >25×109/L, circulating blasts ≧1%,and presence of constitutional symptoms. The presence of 0, 1, 2, and ≧3adverse factors defines low, intermediate-1, intermediate-2, andhigh-risk disease, respectively. The corresponding median survivals were11.3, 7.9, 4, and 2.3 years, respectively. In certain aspects, thedisclosure relates to methods and uses of TβRII antagonists to treat,prevent, or reduce the progression rate and/or severity of myelofibrosisin a patient that has low, intermediate-1, intermediate-2, and/orhigh-risk myelofibrosis according to the IPSS. In some embodiments, thedisclosure relates to methods and uses of TβRII antagonists to preventor delay myelofibrosis risk progression according to the IPSS (e.g.,prevents or delays risk progression from low to intermediate-1 risk,intermediate-1 to intermediate-2 risk, and/or intermediate-2 to highrisk according to the IPSS). In some embodiments, the disclosure relatesto methods and uses of TβRII antagonists to promote or increasemyelofibrosis risk regression according to the IPSS (e.g., promotes orincrease regression from high to intermediate-2 risk, intermediate-2 tointermediate-1 risk, and/or intermediate-1 to low risk according to theIPSS).

The IWG-MRT subsequently developed a dynamic prognostic model (dynamicinternational prognostic scoring system [DIPSS]) that uses the sameprognostic variables used in IPSS but can be applied at any time duringthe disease course [Passamonti F et al. (2010) Blood. 115:1703-1708].DIPSS assigns two, instead of one, adverse points for hemoglobin <10g/dL and risk categorization is accordingly modified: low (0 adversepoints), intermediate-1 (1 or 2 points), intermediate-2 (3 or 4 points),and high (5 or 6 points). The corresponding median survivals were notreached, 14.2, 4, and 1.5 years. In certain aspects, the disclosurerelates to methods and uses of TβRII antagonists to treat, prevent, orreduce the progression rate and/or severity of myelofibrosis in apatient that has low, intermediate-1, intermediate-2, and/or high-riskmyelofibrosis according to the DIPSS. In some embodiments, thedisclosure relates to methods and uses of TβRII antagonists to preventor delay myelofibrosis risk progression according to the DIPSS (e.g.,prevents or delays risk progression from low to intermediate-1 risk,intermediate-1 to intermediate-2 risk, and/or intermediate-2 to highrisk according to the DIPSS). In some embodiments, the disclosurerelates to methods and uses of TβRII antagonists to promote or increasemyelofibrosis risk regression according to the DIPSS (e.g., promotes orincrease regression from high to intermediate-2 risk, intermediate-2 tointermediate-1 risk, and/or intermediate-1 to low risk according to theDIPSS).

IPSS- and DIPSS-independent risk factors for survival in myelofibrosiswere subsequently identified and included unfavorable karyotype (i.e.,complex karyotype or sole or two abnormalities that include +8, −7/7q−,i(17q), inv(3), −5/5q−, 12p−, or 11q23 rearrangement) [Hussein et al.(2010) Blood. 115:496-499], red cell transfusion need [Tefferi et al.(2009) Am J Hematol. 85:14-17], and platelet count <100×109/L [Patnaiket al. (2010) Eur J Haematol. 84:105-108]. Accordingly, DIPSS wasmodified into DIPSS-plus by incorporating these three additionalDIPSS-independent risk factors: platelet count <100×109/L, red celltransfusion need, and unfavorable karyotype. The four DIPS S-plus riskcategories based on the aforementioned eight risk factors are low (norisk factors), intermediate-1 (one risk factor), intermediate-2 (two orthree risk factors), and high (four or more risk factors) withrespective median survivals of 15.4, 6.5, 2.9, and 1.3 years. In certainaspects, the disclosure relates to methods and uses of TβRII antagoniststo treat, prevent, or reduce the progression rate and/or severity ofmyelofibrosis in a patient that has low, intermediate-1, intermediate-2,and/or high-risk myelofibrosis according to the DIPSS-plus. In someembodiments, the disclosure relates to methods and uses of TβRIIantagonists to prevent or delay myelofibrosis risk progression accordingto the DIPS S-plus (e.g., prevents or delays risk progression from lowto intermediate-1 risk, intermediate-1 to intermediate-2 risk, and/orintermediate-2 to high risk according to the DIPSS-plus). In someembodiments, the disclosure relates to methods and uses of TβRIIantagonists to promote or increase myelofibrosis risk regressionaccording to the DIPSS-plus (e.g., promotes or increase regression fromhigh to intermediate-2 risk, intermediate-2 to intermediate-1 risk,and/or intermediate-1 to low risk according to the DIPS S-plus).

Since the publication of DIPSS-plus, several studies that suggestadditional prognostic information have been published. For example,a >80% 2-year mortality in myelofibrosis was predicted by monosomalkaryotype, inv(3)/i(17q) abnormalities, or any two of circulatingblasts >9%, leukocytes ≧40×109/L or other unfavorable karyotype [Tefferiet al. (2011) Blood. 118:4595-4598.]. Similarly, inferior survival inmyelofibrosis has been associated with nullizygosity for JAK2 46/1haplotype, low JAK2V617F allele burden, or presence of IDH, EZH2, SRSF2,or ASXL1 mutations [Tefferi, Ayalew (2014) Am. J. Hematol. 89:916-925].In contrast, the presence or absence of JAK2V617F, MPL, or TET2mutations did not appear to affect survival. Survival in myelofibrosiswas also affected by increased serum IL-8 and IL-2R levels as well asserum free light chain levels, both independent of DIPSS-plus. Mostrecently, Tefferi et al. studied 254 patients with myelofibrosis andreported mutational frequencies of 58% for JAK2, 25% CALR, 8% MPL, and9% wild-type for all three mutations (i.e., triple-negative) [Tefferi etal. (2014) Leukemia. prepublished as DOI 10.1038/leu.2014.3]. CALRmutational frequency in JAK2/MPL-unmutated cases was 74%. CALR mutationswere associated with younger age, higher platelet count, and lowerDIPSS-plus score. CALR-mutated patients were also less likely to beanemic, require transfusions, or display leukocytosis. Spliceosomemutations were infrequent in CALR-mutated patients. In a subsequentinternational study of 570 patients, the authors reported the longestsurvival in CALR+ASXL1 patients (median 10.4 years) and shortest inCALRASXL1+patients (median 2.3 years) [Tefferi et al. (2014) Leukemia.prepublished as DOT 10.1038/leu.2014.57]. CALR+ASXL1+ and CALRASXL1patients had similar survival and were grouped together in anintermediate risk category (median survival 5.8 years). As is becomingevident for overall survival, leukemia-free survival is alsosignificantly compromised in patients carrying certain mutationsincluding IDH and SRSF2 [Tefferi et al. (2012) Leukemia. 26:475-480;Lasho et al. (2012) Blood. 120:4168-4171]. In addition, mutations in LNKand THPO have also been associated with myelofibrosis.

In certain aspects, the disclosure relates to methods and uses of TβRIIantagonists to treat, prevent, or reduce the progression rate and/orseverity of myelofibrosis in a patient that has one or more of:monosomal karyotype, inv(3)/i(17q) abnormalities, circulating blasts >9%and/or leukocytes ≧40×109/L, nullizygosity for JAK2 46/1 haplotype,JAK2V617F mutation, IDH1 mutation, IDH2 mutation, EZH2 mutation, SRSF2mutation, ASXL1 mutation, increased serum IL-8 levels, increased serumIL-2R levels, increased free light chain levels, JAK1 mutation, JAK2mutation, JAK3 mutation, TYK2 mutation, MPL mutation, CALR mutation,CALR+ASXL1−, CALR−ASKL1+, CALR+ASKL1+, CALR−ASKL1−, TET2 mutation, THPOmutation, and LNK mutation.

In general, PV is characterized by an increased red blood cell mass[Vardiman et al. (2009) Blood. 114:937-951; Stuart et al. (2004) Am FamPhysician 69:2139-2144; Hensley et al. (2013) Expert Opin Pharmacother14:609-617; Passamonti F. (2012) Blood 120:275-2845; and Vannucchi A. M.(2010) Intern Emerg Med. 5:177-184]. Patients with PV typically haveexcessive proliferation of not only erythroid but also myeloid andmegakaryocytic components in the bone marrow, resulting in high redblood cell, white blood cell (WBC), and platelet counts. PV patientsgenerally have a reduced quality of life and are at risk oftransformation to secondary MF and acute myeloid leukemia (AML).Therapeutic options are limited (e.g., low-dose aspirin, phlebotomy, andhydroxyurea) and are mainly palliative, focusing on preventing theoccurrence of thrombosis and improving symptoms associated with elevatederythroid, myeloid, and/or megakaryocytic levels.

PV has a much higher prevalence than MF (44-57 per 100,000 persons vs4-6 per 100,000, respectively), and PV patients have a higher risk ofdeath than the general population [Mehta et al. (2014) Leuk Lymphoma55:595-600; and Passamonti et al. (2004) Am J Med. 117:755-761]. PVaffects more men than women, with the median age of diagnosis being 60years; however, approximately 20-25% of patients are younger than 40years [Tibes et al. (2013) Expert Opin Emerg Drugs. 18:393-404]. Themedian survival in patients with PV is around 14 years, but it is muchlower in those older than 60 years and/or with a history of thrombosis(around 8 years) [Tefferi et al. (2013) Leukemia 27:1874-1881].

The understanding of the pathogenesis of PV has greatly improved afterthe discovery of activating mutations in JAK2 in most patients with PV[Levine R L, Pardanani A, Tefferi et al. (2007) Nat Rev Cancer7:673-683; Tefferi A. (2011) Leukemia 25:1059-1063; and Sever et al.(2014) Leuk Lymphoma 55:2685-2690]. The classical JAK2 V617F mutationpresent in approximately 96% of patients with PV and JAK2 exon 12mutations in approximately 3% of patients with PV. Over-activation ofJAK2 autonomously activates downstream pathways, including JAK-STAT,leading to unregulated hematopoiesis. These findings have beeninstrumental in shaping criteria for diagnosis and treatment. Thepresence of the JAK2V617F mutation is a major criterion in the diagnosisof PV, and several JAK2 inhibitors are in development as targetedmolecular therapies for PV [Hensley et al. (2013) Expert OpinPharmacother 14:609-617].

PV diagnosis is currently based on the 2008 World Health Organization(WHO) diagnostic criteria [Vardiman et al. (2009) Blood. 114:937-951].The WHO diagnostic criteria emphasize laboratory values, morphologicfeatures, and genetic data, with erythrocytosis being the first majorcriterion. According to the WHO, evidence of erythrocytosis includeselevated hemoglobin (Hgb) levels (>18.5 g/dL in men and >16.5 g/dL inwomen), but other groups, such as the British Committee for Standards inHaematology and the Polycythemia Vera Study Group, emphasize the use ofelevated hematocrit (Hct) value (>48% in women and >52% in men) or redcell mass measurement, respectively [McMullin et al. (2007) Br JHaematol 138:821-822; and Murphy S. (1999) Semin Hematol 36:9-13].Recently, some investigators have proposed revising the WHO criteria,especially following the identification of masked PV (mPV) in a subgroupof patients with PV [Barbui T et al. (2014) Leukemia 28:1191-1195; andBarbui et al. (2014) Am J Hematol 89:199-202] Unlike patients with overtPV, patients with mPV tend to have normal or borderline Hgb and Hctvalues but are usually positive for JAK2 mutations, have bone marrowfeatures consistent with PV, and have low serum erythropoietin levels.It has been proposed that a revision to the current WHO diagnosticcriteria with emphasis on a lower Hgb threshold and/or the use of Hctthreshold values may be helpful in accurately diagnosing those with mPVand could allow for appropriate and prompt treatment of these patients.

In the current risk stratification model, age ≧60 years of age andhistory of thrombosis are the two risk factors used to classify patientswith PV into low (0 risk factors) and high (one or two risk factors)risk groups. In certain aspects, the disclosure relates to methods anduses of TβRII antagonists to treat, prevent, or reduce the progressionrate and/or severity of PV or one or more complications of PV in apatient that has low or high risk PV. In some embodiments, thedisclosure relates to methods and uses of TβRII antagonists to preventor delay PV risk progression (e.g., prevent or delay risk progressionfrom low to high risk PV). In some embodiments, the disclosure relatesto methods and uses of TβRII antagonists to promote or increase PV riskregression (e.g., promotes or increases regression from high to low riskPV). In some embodiments, the disclosure relates to methods and uses ofTβRII antagonists to prevent or delay PV progression into myelofibrosis(post-PV myelofibrosis). PV also carries a risk of transformation intoacute leukemia [Vannucchi A. M. (2010) Intern Emerg Med. 5:177-184]. Theincidence of transformation to AML in patients with PV ranges from 5 to15% after 10 years of disease, with progressive risk over time [Finazziet al. (2005) Blood 105:2664-2670]. Advanced age, female sex, and theuse of alkylating drugs, radiation, or a combination of cytoreductivedrugs are associated with a higher risk of leukemic transformation. Insome embodiments, the disclosure relates to methods and uses of TβRIIantagonists to prevent or delay PV progression into AML.

Symptomatic burden in PV is generally severe and present in mostpatients with the disease [Scherber et al. (2011) Blood 118:401-408; andHensley et al. (2013) Expert Opin Pharmacother 14:609-617]. The mostcommon complaints are fatigue (reported by 88% of patients), pruritus(62%), night sweats (52%), bone pain (50%), fever (18%), and weight loss(31%), with pruritus and fatigue being the most prevalent andtroublesome symptoms. Pruritus presents as generalized burning,pricking, tingling, or itching and is frequently reported after watercontact (aquagenic pruritus), large temperature shifts, alcoholconsumption, or exercise may induce comparable symptoms. Fatigue hasbeen identified as the consequence of elevated circulating cytokines(e.g., tumor necrosis factor alpha, interleukin-1, and interleukin-6).Additionally, approximately 35 to 45% of patients develop splenomegaly,although its presence is usually indicative of advanced disease [Tefferiet al. (2013) Leukemia 27:1874-1881]. Splenomegaly usually results insecondary symptoms, including abdominal pain, early satiety, weightloss, and nausea, and complications can lead to abdominal organcompression and portal hypertension. PV-associated constitutionalsymptoms and symptoms associated with splenomegaly are present in 70% ofpatients and compromise quality of life [Scherber et al. (2011) Blood118:401-408; Hensley et al. (2013) Expert Opin Pharmacother 14:609-617;and Abelsson et al. (2013) Leuk Lymphoma 54:2226-2230], as assessed bytools such as the European Organisation for Research and Treatment ofCancer Quality of Life Questionnaire Core 30 and/or the MPN-SymptomAssessment Form (SAF) questionnaires. The MPN-SAF Total Symptom Score isa ten-item scoring instrument focusing on fatigue, concentration, earlysatiety, inactivity, night sweats, itching, bone pain, abdominaldiscomfort, weight loss, and fevers. Based on these tools, the symptomburden in patients with PV at diagnosis has been found to be comparableto or worse than that observed in patients with newly diagnosed primaryMF.

Some of the most frequent complications of PV are vascular andthromboembolic events and hemorrhages [Vannucchi A. M. (2010) InternEmerg Med. 5:177-184]. Thrombosis is a prominent symptom observed in upto 39% of patients with PV at diagnosis [Tefferi et al. (2007) SeminThromb Hemost 33:313-320; and Barbui T et al. (2012) Blood Rev26:205-211]. The most frequent types of major thrombosis include stroke,transient ischemic attack, myocardial infarction, peripheral arterialthrombosis, deep venous thrombosis, portal vein thrombosis, andthrombosis of the hepatic veins causing Budd-Chiari syndrome. Inaddition to macrovascular complications, patients may experiencemicrovascular symptoms (e.g., headaches, dizziness, visual disturbances,distal paresthesia, acrocyanosis), with erythromelalgia being the mostcharacteristic disturbance and consisting of congestion, redness, andburning pain in the extremities. In cases of extreme thrombocytosis(e.g., >1500×10⁹/L), patients may be at risk for developing acquired vonWillebrand syndrome, which causes a bleeding diathesis [Chou Y S et al.(2013) Eur J Haematol 90:228-236]. Hemorrhage is also a significantcause of morbidity and mortality in patients with PV, with a cumulativeincidence of 39.6% (6.2% per person-year). Additionally, overallsurvival has been found to be significantly shorter among patients withhemorrhage than among those without this complication (median overallsurvival, around 95 months).

In certain aspects, a TβRII antagonist (e.g., a TβRII polypeptidecomprising, consisting essential of, or consisting of an amino acidsequence that is at least 85%, 90%, 91%, 92%, 93%, 94% 95%, 96%, 97%,98%, 99%, or 100% identical to the amino acid sequence of any one of SEQID NOs: 5-17, 25, 27, 29, 31, 33, 35, 37, 39, 41, 43, 47-49, 53-62, 101,and 103-105) may be used, alone or in combination with one or moresupportive therapies or active agents (e.g., a Janus kinase inhibitorsuch as ruxolitinib), to treat, prevent, or reduce the progression rateand/or severity of polycythemia vera. In particular, TβRII antagonistsmay be used, alone or in combination with one or more supportivetherapies or active agents, to treat, prevent, or reduce the progressionrate and/or severity of one or more complications of polycythemia vera.Complications of polycythemia vera that may be treated in accordancewith the methods disclosed herein include, for example, excessiveproliferation of erythroid cells, excessive proliferation of myeloidcells, excessive proliferation of megakaryocytic cells, high red bloodcell levels, high white blood cell levels, high platelet levels,fatigue, pruritus, night sweats, bone pain, fever, and weight loss,elevated inflammatory cytokines (e.g., IL-6), inflammatorycomplications, IL-6-mediated inflammatory complications, splenomegaly,abdominal pain, early satiety, weight loss, nausea, abdominal organcompression, portal hypertension, constitutional symptoms, vascularcomplications, thrombosis, microvascular complications, andmacrovascular complications.

The new World Health Organization (WHO) diagnostic criteria foressential thrombocythemia (ET) issued in 2008 made an importantdistinction between true ET and early myelofibrosis and thus helped toidentify a more homogenous population for diagnosis, which arecharacterized, in part, by longer survival and less transformation toovert MF. Thrombocytosis is a prerequisite for the diagnosis of ET, butsuch events may also manifest in PV and PMF patients, although moreseldom [Birgegard G. (2015) Ther Adv Hematol 6(3):142-156]. In addition,ET is characterized by lower white blood cell counts, lower hemoglobinlevels, low lactate dehydrogenase (LDH) levels in plasma and,importantly, a better prognosis, that early myelofibrosis patients[Barbui et al. (2012) Blood 120: 569-571.]. A recent prognostic modelfor WHO-classified ET indicates that expected survival from diagnosis is13.7 years for high risk patients, 24.5 years for an intermediate groupand >25 years for low risk patients [Passamonti et al. (2012) Blood 120:1197-1201]. The distinction between true ET and early MF, so far, has nogreat consequences for the pharmacological treatment, since this isdirected by risk stratification for thrombohemorrhagic events, but it isof course important in communications with the patients and may soon bevery important for treatment decisions with the new drugs underdevelopment.

The detection of driver mutations in ET and other myelofibrosisconditions has greatly increased understanding of the pathophysiology ofthe disease. As discussed previously, a breakthrough in myelofibrosisresearch was made when a mutation in the pseudokinase domain of the JAK2gene was discovered to be present in a large percentage of myelofibrosispatients. Interestingly, while around 95% of PV patients carry theJAK2V617F mutation, only around 50% of ET patients are JAK2 mutationpositive [Campbell et al. (2005) Lancet 366:1945-1953]. Moreover,JAK2V617F+ET patients manifest a slightly different phenotypic patternthan JAK2V617F−ET patients, presenting with higher Hb and WBC levels,lower serum erythropoietin, and lower platelets. Several studiesdemonstrate that there is an increased risk of thrombosis inJAK2V617F+ET patients compared to JAK2V617F−ET patients [Ziakas P.(2008) Haematologica 93:1412-1414; Dahabreh et al. (2009) Leuk Res 33:67-73; and Lussana et al. (2009) Thromb Res 124: 409-417]. A recentstudy showed that progression of JAK2V617F allele burden, particularlyat high stable levels, was significantly correlated to development of MF[Alvarez-Larran A et al. (2014b) Am J Hematol 89: 517-523].

A recent addition to the mutational pattern in myelofibrosis is thedetection of a driver mutation of CALR, a highly conservedmultifunctional endoplasmic reticulum protein with partly unknownfunctions. The mutation is found in ET and PMF patients, but almostexclusively in ones that do not have mutations in either JAK2 or MPL[Klampfl et al. (2013) N Engl J Med 369: 2379-2390; Nangalia et al.(2013) N Engl J Med 369: 2391-2405]. The frequency is around 20% in bothET and PMF, which means that about 85% of ET patients can now bediagnosed with a molecular marker. Interestingly, the CALR mutation inET produces a phenotype profile with clear differences fromJAK2V617F+patients. Compared with JAK2V617F+patients, CALR+patients areyounger, more commonly male, have higher platelet levels, and lowerleukocyte levels [Gangat et al. (2014) Eur J Haematol 94: 31-36; Rotunnoet al. (2014) Blood 123: 1552-1555; Rumi et al. (2014) Blood 123:2416-2419; Tefferi et al. (2014c) Leukemia 28: 2300-2303]. In addition,the difference in thrombotic rate is quite marked: the 10-yearcumulative incidence being 5.1% (JAK2V617F+patients), and 14.5%(CALR+patients), respectively, and correspondingly, the 15-year rate10.5% (JAK2V617F+patients) and 25.1% (CALR+patients).

In the current risk stratification model, age ≧60 years of age andhistory of thrombosis are the two risk factors used to classify patientswith ET into low (0 risk factors) and high (one or two risk factors)risk groups. In certain aspects, the disclosure relates to methods anduses of TβRII antagonists to treat, prevent, or reduce the progressionrate and/or severity of ET or one or more complications of ET in apatient that has low or high risk ET. In some embodiments, thedisclosure relates to methods and uses of TβRII antagonists to preventor delay ET risk progression (e.g., prevent or delay risk progressionfrom low to high risk ET). In some embodiments, the disclosure relatesto methods and uses of TβRII antagonists to promote or increase ET riskregression (e.g., promotes or increases regression from high to low riskET). In some embodiments, the disclosure relates to methods and uses ofTβRII antagonists to prevent or delay ET progression into myelofibrosis(post-ET myelofibrosis). ET also carries a risk of transformation intoacute leukemia [Vannucchi A. M. (2010) Intern Emerg Med. 5:177-184]. Insome embodiments, the disclosure relates to methods and uses of TβRIIantagonists to prevent or delay ET progression into AML.

Studies have shown that ET patients have a significant symptom burdenwith an effect on quality of life. In an international effort, a symptomassessment tool specific to the MPN population was developed andvalidated [Emanuel et al. (2012) J Clin Oncol 30: 4098-4103; andScherber et al. (2011) Blood 118: 401-408]. Symptoms/complications of ETinclude, for example: fatigue, night sweats, nausea, numbness, visionsdisturbances, and weight loss, as well as resulting from microvascularcomplications like headache, chest pain, dizziness and erythromelalgia.Additionally, about 20% of ET patients have experienced thrombosisbefore or at diagnosis. Mild splenomegaly is also frequently observed inET patients.

In certain aspects, a TβRII antagonist (e.g., a TβRII polypeptidecomprising, consisting essential of, or consisting of an amino acidsequence that is at least 85%, 90%, 91%, 92%, 93%, 94% 95%, 96%, 97%,98%, 99%, or 100% identical to the amino acid sequence of any one of SEQID NOs: 5-17, 25, 27, 29, 31, 33, 35, 37, 39, 41, 43, 47-49, 53-62, 101,and 103-105) may be used, alone or in combination with one or moresupportive therapies or active agents (e.g., a Janus kinase inhibitorsuch as ruxolitinib), to treat, prevent, or reduce the progression rateand/or severity of essential thrombocythemia. In particular, TβRIIantagonists may be used, alone or in combination with one or moresupportive therapies or active agents, to treat, prevent, or reduce theprogression rate and/or severity of one or more complications ofessential thrombocythemia. Complications of essential thrombocythemiathat may be treated in accordance with the methods disclosed hereininclude, for example, thrombocytosis, fatigue, night sweats, nausea,numbness, visions disturbances, weight loss, microvascularcomplications, macrovascular complications, headache, chest pain,dizziness, erythromelalgia, thrombosis, splenomegaly, elevatedinflammatory cytokines, inflammatory complication, IL-6 inflammatorycomplication, elevated inflammatory cytokine levels, elevated IL-6levels, vasculature complications, and hemorrhage.

As discussed above, the discovery of a Janus kinase 2 (JAK2)gain-of-function mutation, JAK2V617F, has led to significantimprovements in the understanding of the biology underlyingmyelofibrosis, as well as the development of ruxolitinib, a JAK2inhibitor which is the first drug approved by the FDA for the treatmentof myelofibrosis [Baxter et al. (2005) Lancet 365:1054-1061; James C. etal. (2005) Nature 434:1144-1148; Kralovics et al. (2005) N Engl J Med.352:1779-1790; and Levine et al. (2005) Cancer Cell 7:387-397].JAK2V617F is present in the majority of myelofibrosis (50-60%) and PV(95%) patients and about half ET (˜50%) patients [Baxter et al. (2005)Lancet 365:1054-1061; James C. et al. (2005) Nature 434:1144-1148;Kralovics et al. (2005) N Engl J Med. 352:1779-1790; Levine et al.(2005) Cancer Cell 7:387-397; and Quintas-Cardama et al. (2011) Nat RevDrug Discov 10:127-140]. Additional mutations relevant to the JAKSTATpathway have been identified in patients with myeloproliferativedisorders including, for example, MPL, CALR, LNK, TET2, IDH1, IDH2,THPO, and ASXL1 [Pikman et al. (2006) PLoS Med 3:e270; Oh et al. (2010)Blood 116:988-992; Delhommeau et al. (2009) N Engl J Med 360:2289-2301;and Carbuccia et al. (2009) Leukemia 23:2183-2186]. JAK2V617F and othermutations may occur in the same patient at the same time, and multipleclones with different mutational profiles can occur in a single patient.The presence of JAK2V617F has been correlated to worsening of symptomsand progression stage of myeloproliferative disease to advanced stages[Barosi et al. (2007) Blood 110:4030-4036; and Tefferi et al. (2005) BrJ Haematol 131:320-328

With the discovery of these genetic markers, newer therapeuticstrategies are focusing, in part, on achieving a reduction inmyeloproliferative disease-associated allele burden. In the context ofmyeloproliferative diseases, allele burden is generally defined as theratio of mutant copy number (e.g., JAK2V617F) to total gene copy numbera given patient (e.g., JAK2V617F/JAK2V617F+wild-type JAK2]). In somestudies, patients with lower allele burden have demonstrated a betterprognosis than those with higher allele burdens. Several MF studies havelinked high allele burden to progression of disease, for example, onestudy has shown higher allele burden of certain mutant genes isassociated with progressing to AML which is consistent with theobservation that a majority of patients with leukemia are homozygous forJAK2V617F [Barosi et al. (2007) Blood 110:4030-4036; and Passamonti etal. (2010) Leukemia 24:1574-1579]. In addition, studies haveconsistently demonstrated a link between increasing allele burden andworsening splenomegaly and increased myelopoiesis [Passamonti et al.2009) Haematologica 94:7-10].

In certain aspects, the present disclosure provides methods fortreating, preventing, or reducing the progression rate and/or severityof a myeloproliferative disorder [e.g., myelofibrosis (e.g., primarymyelofibrosis, post-polycythemia vera myelofibrosis, and post-essentialthrombocythemia myelofibrosis), polycythemia vera (e.g., maskedpolycythemia vera), and essential thrombocythemia] or one or morecomplications of a myeloproliferative disorder (e.g., fibrosis,splenomegaly, inflammation, anemia, and extramedullary hematopoiesis) byadministering to a patient in need thereof and effective amount of aTβRII antagonist (e.g., a TβRII polypeptide comprising, consistingessential of, or consisting of an amino acid sequence that is at least85%, 90%, 91%, 92%, 93%, 94% 95%, 96%, 97%, 98%, 99%, or 100% identicalto the amino acid sequence of any one of SEQ ID NOs: 5-17, 25, 27, 29,31, 33, 35, 37, 39, 41, 43, 47-49, 53-62, 101, and 103-105), optionallyin combination with one or more additional supportive therapies and/oractive agents for treating a myeloproliferative disorder (e.g., a Januskinase inhibitor such as ruxolitinib) wherein the patient has one ormore myeloproliferative-associated alleles (e.g., JAK2, MPL, CALR, LNK,TET2, IDH1, IDH2, THPO, and ASXL1). In some embodiments, the methodreduces allele burden of one or more myeloproliferative-associatedalleles (e.g., JAK2, MPL, CALR, LNK, TET2, IDH1, IDH2, THPO, and ASXL1)in the patient. In some embodiments, the patient has one or moremyeloproliferative-associated JAK2 alleles. In some embodiments, themethod reduces allele burden of one or moremyeloproliferative-associated JAK2 alleles. In some embodiments, thepatient has the JAK2V617F myeloproliferative-associated allele. In someembodiments, the method reduces JAK2V617F myeloproliferative-associatedallele burden.

In certain aspects, the present disclosure provides methods for reducingmyeloproliferative-associated allele burden in a patient having amyeloproliferative disorder [e.g., myelofibrosis (e.g., primarymyelofibrosis, post-polycythemia vera myelofibrosis, and post-essentialthrombocythemia myelofibrosis), polycythemia vera (e.g., maskedpolycythemia vera), and essential thrombocythemia] by administering to apatient in need thereof and effective amount of a TβRII antagonist(e.g., a TβRII polypeptide comprising, consisting essential of, orconsisting of an amino acid sequence that is at least 85%, 90%, 91%,92%, 93%, 94% 95%, 96%, 97%, 98%, 99%, or 100% identical to the aminoacid sequence of any one of SEQ ID NOs: 5-17, 25, 27, 29, 31, 33, 35,37, 39, 41, 43, 47-49, 53-62, 101, and 103-105), optionally incombination with one or more additional supportive therapies and/oractive agents for treating a myeloproliferative disorder (e.g., a Januskinase inhibitor such as ruxolitinib). In some embodiments, the patienthas one or more myeloproliferative-associated alleles selected from thegroup consisting of: JAK2, MPL, CALR, LNK, TET2, IDH1, IDH2, THPO, andASXL1). In some embodiments, the patient has one or more JAK2myeloproliferative-associated alleles. In some embodiments, the patienthas the JAK2V617F myeloproliferative-associated allele.

In accordance with the methods described herein, a TβRII antagonist(e.g., a TβRII polypeptide comprising, consisting essential of, orconsisting of an amino acid sequence that is at least 85%, 90%, 91%,92%, 93%, 94% 95%, 96%, 97%, 98%, 99%, or 100% identical to the aminoacid sequence of any one of SEQ ID NOs: 5-17, 25, 27, 29, 31, 33, 35,37, 39, 41, 43, 47-49, 53-62, 101, and 103-105) can be administered tothe subject alone, or in combination with one or more additional activeagents or supportive therapies, for example, active agents or supportivetherapies that are useful for treating myeloproliferative disorders(e.g., primary myelofibrosis polycythemia vera, masked polycythemia,essential thrombocythemia, post-polycythemia vera myelofibrosis, andpost-essential thrombocythaemia myelofibrosis) as well as one or morecomplications thereof a myeloproliferative disorders.

As used herein, “in combination with”, “combinations of”, “combinedwith”, or “conjoint” administration refers to any form of administrationsuch that additional therapies (e.g., second, third, fourth, etc.) arestill effective in the body (e.g., multiple compounds are simultaneouslyeffective in the patient, which may include synergistic effects of thosecompounds). Effectiveness may not correlate to measurable concentrationof the agent in blood, serum, or plasma. For example, the differenttherapeutic compounds can be administered either in the same formulationor in separate formulations, either concomitantly or sequentially, andon different schedules. Thus, an individual who receives such treatmentcan benefit from a combined effect of different therapies. One or moreTβRII antagonists of the disclosure can be administered concurrentlywith, prior to, or subsequent to, one or more other additional agents orsupportive therapies. In general, each therapeutic agent will beadministered at a dose and/or on a time schedule determined for thatparticular agent. The particular combination to employ in a regimen willtake into account compatibility of the TβRII antagonist of the presentdisclosure with the therapy and/or the desired effect.

The management of anemia can be one of the most challenging aspects oftreating patients with myelofibrosis [Tefferi A. (2011) Blood117(13):3949-3504; Barosi et al. (2011) Expert Opin Pharmacother12(10):1597-1611]. Blood transfusion (whole blood or red blood celltransfusion) is a standard therapy for symptomatically anemicmyelofibrosis patients. In addition to transfusion, there are a varietyof conventional agents used to treat anemia in these patients. Forexample, erythropoiesis-stimulating agents [e.g., ESAs such aserythropoietin (EPO) and derivatives thereof], androgens (e.g.,testosterone enanthate and fluoxymesterone), prednisone, danazol,thalidomide, prednisone, and lenalidomide are commonly used to treatanemia in myelofibrosis patients. In general, ESAs are used in patientswith moderate, non-transfusion-dependent anemia and low serumerythropoietin levels. Response rates vary from 20-60% with no clearsupport for darbepoetin-alpha versus conventional recombinanterythropoietin. ESAs responses are usually short-lived (around 1 year).If ESAs do not work or have poor efficacy, danazol or androgenpreparations are typically used to treat anemic patients with a responserate around 20%. Low-dose thalidomide in association with taperingprednisone has produced responses in anemia in approximately 20-40% ofpatients [Thapaliya et al. (2011) Am J Hematol 86(1):86-98]. However,thalidomide treatment is often poorly tolerated with peripheralneuropathies, constipation, and somnolence leading to discontinuation ofthe drug in most patients. In myelofibrosis patients withdel(5q31)-associated anemia, lenalidomide is the recommended first linetherapy because significant improvement, with resolution of anemia andoccasionally evidenced of molecular remission, has been reported[Tefferi et al. (2007) Leukemia 21(8):1827-1828].

In certain aspects, the disclosure relates to methods and uses of TβRIIantagonists to treat, prevent, or reduce the progression rate and/orseverity of myelofibrosis in a patient that has anemia. In someembodiments, the disclosure relates to methods and uses of TβRIIantagonists to treat, prevent, or reduce the progression rate and/orseverity of anemia in a myelofibrosis patient. In some embodiments, thedisclosure relates to a method of treating, preventing, or reducing theprogression rate and/or severity myelofibrosis or one or morecomplications of myelofibrosis (e.g., anemia) in a patient in needthereof that comprises administration of one or more TβRII antagonistsconjointly with one or more additional active agents selected from thegroup consisting of: an erythropoiesis-stimulating agent [e.g., ESAssuch as erythropoietin (EPO) and derivatives thereof], androgen (e.g.,testosterone enanthate and fluoxymesterone), prednisone, danazol,thalidomide, prednisone, and lenalidomide. In some embodiments, thedisclosure relates to a method of treating, preventing, or reducing theprogression rate and/or severity of anemia in a myelofibrosis patient inneed thereof of comprises administration of one or more TβRIIantagonists conjointly with one or more additional active agentsselected from the group consisting of: an erythropoiesis-stimulatingagent [e.g., ESAs such as erythropoietin (EPO) and derivatives thereof],androgen (e.g., testosterone enanthate and fluoxymesterone), prednisone,danazol, thalidomide, prednisone, and lenalidomide. In some embodiments,the disclosure relates a method of treating, preventing, or reducing theprogression rate and/or severity anemia in a myelofibrosis patient inneed thereof of comprises administration of one or more TβRIIantagonists conjointly with a blood transfusion (whole blood or redblood cell transfusion).

One or more TβRII antagonists of the disclosure may be used incombination with an EPO receptor activator to achieve an increase in redblood cells, particularly at lower dose ranges. This may be beneficialin reducing the known off-target effects and risks associated with highdoses of EPO receptor activators. The primary adverse effects of ESAsinclude, for example, an excessive increase in the hematocrit orhemoglobin levels and polycythemia. Elevated hematocrit levels can leadto hypertension (more particularly aggravation of hypertension). Otheradverse effects of ESAs which have been reported, some of which relateto hypertension, are headaches, influenza-like syndrome, obstruction ofshunts, myocardial infarctions and cerebral convulsions due tothrombosis, hypertensive encephalopathy, and red cell blood cellaplasia. See, e.g., Singibarti (1994) J. Clin Investig 72(suppl 6),S36-S43; Horl et al. (2000) Nephrol Dial Transplant 15(suppl 4), 51-56;Delanty et al. (1997) Neurology 49, 686-689; and Bunn (2002) N Engl JMed 346(7), 522-523). In certain embodiments, the present disclosureprovides methods of treating or preventing anemia in a myelofibrosispatient by administering to the patient a therapeutically effectiveamount of one or more TβRII antagonists and an EPO receptor activator.In certain embodiments, a TβRII antagonist of the disclosure may be usedin combination with EPO receptor activators to reduce the required doseof these activators in patients that are susceptible to adverse effectsof ESAs. These methods may be used for therapeutic and prophylactictreatments of a patient.

When monitoring hemoglobin and/or hematocrit levels in humans, a levelof less than normal for the appropriate age and gender category may beindicative of anemia, although individual variations are taken intoaccount. For example, a hemoglobin level from 10-12.5 g/dl, andtypically about 11.0 g/dl is considered to be within the normal range inhealthy adults, although, in terms of therapy, a lower target level maycause fewer cardiovascular side effects. See, e.g., Jacobs et al. (2000)Nephrol Dial Transplant 15, 15-19. Alternatively, hematocrit levels(percentage of the volume of a blood sample occupied by the cells) canbe used as a measure of anemia. Hematocrit levels for healthyindividuals range from about 41-51% for adult males and from 35-45% foradult females. In certain embodiments, a patient may be treated with adosing regimen (e.g., TβRII antagonist optionally in combination withone or more additional active agents or supportive therapies) intendedto restore the patient to a target level of red blood cells, hemoglobin,and/or hematocrit or allow the reduction or elimination of red bloodcell transfusions (reduce transfusion burden) while maintaining anacceptable level of red blood cells, hemoglobin and/or hematocrit. Ashemoglobin and hematocrit levels vary from person to person, optimally,the target hemoglobin and/or hematocrit level can be individualized foreach patient.

In patients who receive frequent transfusions of whole blood or redblood cells, normal mechanisms of iron homeostasis can be overwhelmed,eventually leading to toxic and potentially fatal accumulation of ironin vital tissues such as heart, liver, and endocrine glands. Regular redblood cell transfusions require exposure to various donor units of bloodand hence a higher risk of alloimmunization. Difficulties with vascularaccess, availability of and compliance with iron chelation, and highcost are some of the reasons why it can be beneficial to limit thenumber of red blood cell transfusions.

In certain aspects, one or more TβRII antagonists, optionally combinedwith an EPO receptor activator, may be used in combination with one ormore iron-chelating agents to treat, prevent, or reduce the progressionrate and/or severity of iron overload in a myelofibrosis patient. Insome embodiments, one or more TβRII antagonists, optionally combinedwith an EPO receptor activator, may be used in combination with one ormore iron-chelating agents to treat, prevent, or reduce the progressionrate and/or severity of tissue iron overload [e.g., spleen (splenic),liver (hepatic), heart (cardiac) iron overload] in a myelofibrosispatient. Effective iron-chelating agents should be able to selectivelybind and neutralize ferric iron, the oxidized form of non-transferrinbound iron which likely accounts for most iron toxicity throughcatalytic production of hydroxyl radicals and oxidation products [see,e.g., Esposito et al. (2003) Blood 102:2670-2677]. These agents arestructurally diverse, but all possess oxygen or nitrogen donor atomsable to form neutralizing octahedral coordination complexes withindividual iron atoms in stoichiometries of 1:1 (hexadentate agents),2:1 (tridentate), or 3:1 (bidentate) [Kalinowski et al. (2005) PharmacolRev 57:547-583]. In general, effective iron-chelating agents also arerelatively low molecular weight (e.g., less than 700 daltons), withsolubility in both water and lipids to enable access to affectedtissues. Specific examples of iron-chelating molecules includedeferoxamine, a hexadentate agent of bacterial origin requiring dailyparenteral administration, and the orally active synthetic agentsdeferiprone (bidentate) and deferasirox (tridentate). Combinationtherapy consisting of same-day administration of two iron-chelatingagents shows promise in patients unresponsive to chelation monotherapyand also in overcoming issues of poor patient compliance withdereroxamine alone [Cao et al. (2011) Pediatr Rep 3(2):e17; andGalanello et al. (2010) Ann NY Acad Sci 1202:79-86].

In the management of patients with a myeloproliferative disorder (e.g.,myelofibrosis, polycythemia vera, and essential thrombocytopenia),cytoreductive agents have been the treatment of choice for most patientswith symptomatic splenomegaly. Hydroxycarbamide (hydroxyurea, HC) is themost commonly used cytoreductive agent, which usually produces modestresponses at higher doses. However, HC can often exacerbate cytopeniasand therefore is often not well tolerated. Reductions in spleen sizefrom 25%-50% have been reported in up to 35% of the patients treatedwith HC [Martinez-Trillos et al. (2010) Ann Hematol. 89(12):1233-1237].In patients who do not respond to HC, busulfan or melphalan may be used,especially in older patients, since there is evidence that these agentscan increase the frequency of leukemic transformation. Spleen responseswith low-dose thalidomide are low (<20%). However, lenalidomide has beenshown to result in a 33% response rate in a study that included somepatients who had failed prior thalidomide therapy. In cases of massiverefractory splenomegaly, monthly intravenous cladribine courses haveproduced responses up to 50%, with severe but reversible cytopeniasbeing the primary toxicity [Faoro et al. (2005) Eur J Haematol74(2):117-120]. Ruxolitinib has proven superior to HC in recent studiesand thus is becoming first line agent to control symptomatic orprogressive splenomegaly. Other JAK inhibitors (e.g., SAR302503, CYT387,pacritinib, AZD-1480, BMS-911543, NS-018, LY2784544, lestaurtinib,SEP-701, and AT-9283) are being evaluated for use in treating MF, ET,and PV and thus may be useful in reducing splenomegaly such patients.

While the management of myeloproliferative disease-associatedsplenomegaly with splenectomy is well established, the procedure isassociated with morbidity and mortality rates of approximately 31% and9%, respectively [Mesa R A. (2009) Blood 113(22):5394-5400]. Hepaticextramedullary hematopoiesis, which sometimes leads to rapid hepaticenlargement, is an unusual but well recognized complication followingsplenectomy, as is the increased thrombotic risk. As a result,splenectomy is generally restricted to selected patients with refractoryhemolysis or anemia, symptomatic splenomegaly, significant splenicinfarction, severe portal hypertension, and/or severe hypercatabolicsymptoms. Radiotherapy can be an alternative to splenectomy in patientswith symptomatic splenomegaly and an adequate platelet count. However,studies have shown that 44% of patients experienced cytopenias,following radiotherapy, of which 13% were fatal [Elliott M A et al.(1999) Blood Rev. 13(3):163-170]. Low-dose radiotherapy remains apreferred treatment for nonsplenic extramedullary hematopoiesis,including involvement of the peritoneum and pleura with resultantascites and pleural effusions.

In certain aspects, the present disclosure provides methods fortreating, preventing, or reducing the progression rate and/or severityof a myeloproliferative disorder (e.g., primary myelofibrosis,polycythemia vera, masked polycythemia, essential thrombocythemia,post-polycythemia vera myelofibrosis, and post-essential thrombocythemiamyelofibrosis) or one or more complications of a myeloproliferativedisorder comprising administering to a patient in need thereof aneffective amount of a TβRII antagonist (e.g., a TβRII polypeptidecomprising, consisting essential of, or consisting of an amino acidsequence that is at least 85%, 90%, 91%, 92%, 93%, 94% 95%, 96%, 97%,98%, 99%, or 100% identical to the amino acid sequence of any one of SEQID NOs: 5-17, 25, 27, 29, 31, 33, 35, 37, 39, 41, 43, 47-49, 53-62, 101,and 103-105) in combination with one or more active agents or supportivetherapies for treating splenomegaly and/or extramedullary hematopoiesis.Active agents or supportive therapies for treating splenomegaly and/orextramedullary hematopoiesis include, for example, cytoreductive agents,thalidomide (e.g., Immunoprin, Talidex, Talizer, and Thalomid),lenalidomide (e.g., Revlimid), hydroxyurea (e.g., Apo-Hydroxyurea,Droxia, and Hydrea), busulfan (e.g., Myleran and Busulfex IV), melphalan(e.g., Alkeran and Sarcolysin), cladribine (e.g., Leustatin, Litak, andMovectro), splenectomy, radiotherapy, JAK inhibitors (e.g., ruxolitinib,SAR302503, CYT387, pacritinib, AZD-1480, BMS-911543, NS-018, LY2784544,lestaurtinib, SEP-701, and AT-9283).

Patients with myeloproliferative disorders (e.g., primary myelofibrosispolycythemia vera, masked polycythemia, essential thrombocythemia,post-polycythemia vera myelofibrosis, and post-essentialthrombocythaemia myelofibrosis) suffer from an increased risk of majorcardiovascular events [Barbui et al. (2010) Blood 115(4):778-782]. Fataland nonfatal thromboses were reported in 7.2% PMF patients included in amulti-institutional series, with a rate of 1.75% patient-years notdissimilar from that reported in ET (1%-3% patient-year). Risk factorsfor thrombosis were age >60 years and a JAK2V617F mutational status,particularly if the latter was associated with leukocytosis. Hydroxyureaand low-dose aspirin is generally prescribed to treat or preventthrombosis in MF patients.

In certain aspects, the present disclosure provides methods fortreating, preventing, or reducing the progression rate and/or severityof a myeloproliferative disorder (e.g., primary myelofibrosis,polycythemia vera, masked polycythemia, essential thrombocythemia,post-polycythemia vera myelofibrosis, and post-essential thrombocythemiamyelofibrosis) or one or more complications of a myeloproliferativedisorder comprising administering to a patient in need thereof aneffective amount of a TβRII antagonist (e.g., a TβRII polypeptidecomprising, consisting essential of, or consisting of an amino acidsequence that is at least 85%, 90%, 91%, 92%, 93%, 94% 95%, 96%, 97%,98%, 99%, or 100% identical to the amino acid sequence of any one of SEQID NOs: 5-17, 25, 27, 29, 31, 33, 35, 37, 39, 41, 43, 47-49, 53-62, 101,and 103-105) in combination with one or more active agents or supportivetherapies for treating thrombosis. Active agents or supportive therapiesfor treating thrombosis include, for example, hydroxyurea (e.g.,Apo-Hydroxyurea, Droxia, and Hydrea) and aspirin

In certain aspects, the present disclosure provides methods fortreating, preventing, or reducing the progression rate and/or severityof a myeloproliferative disorder (e.g., primary myelofibrosis,polycythemia vera, masked polycythemia, essential thrombocythemia,post-polycythemia vera myelofibrosis, and post-essential thrombocythemiamyelofibrosis) or one or more complications of a myeloproliferativedisorder comprising administering to a patient in need thereof aneffective amount of a TβRII antagonist (e.g., a TβRII polypeptidecomprising, consisting essential of, or consisting of an amino acidsequence that is at least 85%, 90%, 91%, 92%, 93%, 94% 95%, 96%, 97%,98%, 99%, or 100% identical to the amino acid sequence of any one of SEQID NOs: 5-17, 25, 27, 29, 31, 33, 35, 37, 39, 41, 43, 47-49, 53-62, 101,and 103-105) in combination with one or more JAK inhibitors. JAKinhibitors that may be used in accordance with the methods of thedisclosure include, for example, ruxolitinib, fedratinib (SAR302503),monoelotinib (CYT387), pacritinib, lestaurtinib, AZD-1480, BMS-911543,NS-018, LY2784544, SEP-701, XL019, and AT-9283.

In addition to JAK2 inhibition, several other treatment strategies areunder investigation for the treatment of myeloproliferative disorders,including immunomodulating drugs (IMiDs), inhibitors of the mammaliantarget of rapamycin (mTOR) pathway, and epigenetic factors modulators[Mascarenhas et al. (2013) Haematologica 98(10):1499-1509].

Pomalidomide is a second-generation immunomodulatory drug underevaluation in a range of doses for treatment of MF, PV, and ET [Begna etal. (2011) Leukemia 25:301-304; and Mesa et al. (2010) Am J Hematol85:129-130]. A phase 2 trial evaluating low-dose pomalidomide andprednisone in 58 patients reported anemia responses in 24% of theJAK2V617F-positive patients. Anemia responses were absent in thosewithout the mutation, and predicted by pomalidomide-induced basophiliaand the absence of marked splenomegaly. An analysis of 82 evaluablepatients with MF enrolled in three consecutive phase 1 and 2 clinicaltrials from 2007 to 2010 demonstrated an anemia response in 27% ofpatients according to IWG-MRT criteria. Anemia response occurred mostoften in the first 6 months of treatment, in the presence of JAK2V617F,and in the absence of marked splenomegaly.

In certain aspects, the present disclosure provides methods fortreating, preventing, or reducing the progression rate and/or severityof a myeloproliferative disorder (e.g., primary myelofibrosis,polycythemia vera, masked polycythemia, essential thrombocythemia,post-polycythemia vera myelofibrosis, and post-essential thrombocythemiamyelofibrosis) or one or more complications of a myeloproliferativedisorder comprising administering to a patient in need thereof aneffective amount of a TβRII antagonist (e.g., a TβRII polypeptidecomprising, consisting essential of, or consisting of an amino acidsequence that is at least 85%, 90%, 91%, 92%, 93%, 94% 95%, 96%, 97%,98%, 99%, or 100% identical to the amino acid sequence of any one of SEQID NOs: 5-17, 25, 27, 29, 31, 33, 35, 37, 39, 41, 43, 47-49, 53-62, 101,and 103-105) in combination with one or more immunomodulatory agents.Immunomodulatory agents that may be used in accordance with the methodsof the disclosure include, for example, pomalidomide (e.g., Pomalyst andImnovid).

In addition to JAK/STAT, other related pathways, such as thephosphatidylinositol 3-kinase/mammalian target of rapamycin (PI3K/mTOR)pathway, have been found to be dysregulated in myeloproliferativedisorder patients [Tefferi A. (2011) Am J Hematol 86(12):1017-1026]. Inseveral studies, it has been shown that the proliferation of JAK2V617Fpositive cells decreased when treated with the mTOR inhibitor everolimus[Guglielmelli et al. (2011) Blood 118(8):2069-2076; and Vannucchi et al.(2009) Blood 114(22):2914]. Results from a Phase I/II study of 39 high-or intermediate-risk patients with PMF or post-PV/ET MF treated witheverolimus have also been reported. Of 30 evaluable patients, 69% and80% experienced complete resolution of systemic symptoms and pruritus,respectively. The response rate was 60% when European MyelofibrosisNetwork criteria were applied (eight major, seven moderate, and threeminor responses) or 23% when International Working Group forMyelofibrosis Research and Treatment criteria were used (one partialresponse, six clinical improvements). These results provide proof ofconcept that targeting the mTOR pathway may be clinically relevant inpatients with myeloproliferative neoplasms.

In certain aspects, the present disclosure provides methods fortreating, preventing, or reducing the progression rate and/or severityof a myeloproliferative disorder (e.g., primary myelofibrosis,polycythemia vera, masked polycythemia, essential thrombocythemia,post-polycythemia vera myelofibrosis, and post-essential thrombocythemiamyelofibrosis) or one or more complications of a myeloproliferativedisorder comprising administering to a patient in need thereof aneffective amount of a TβRII antagonist (e.g., a TβRII polypeptidecomprising, consisting essential of, or consisting of an amino acidsequence that is at least 85%, 90%, 91%, 92%, 93%, 94% 95%, 96%, 97%,98%, 99%, or 100% identical to the amino acid sequence of any one of SEQID NOs: 5-17, 25, 27, 29, 31, 33, 35, 37, 39, 41, 43, 47-49, 53-62, 101,and 103-105) in combination with one or more mTOR inhibitors. mTORinhibitors that may be used in accordance with the methods of thedisclosure include, for example, rapamycin, sirolimus, deforolimus,everolimus, temsirolimus, NVP-BEZ235, BGT226, SF1126, PK1-587, INK128,AZD8055, and AZD2014.

Histone deacetylase (HDAC) inhibition has an inhibitory effect on theJAK-STAT pathway, and HDAC inhibitors givinostat (ITF2357), panobinostat(LBH589) and pracinostat (SB939) are all currently under investigationfor MF [Quintas-Cardama et al. (2011) Therapy Blood 118(Suppl. 1);Mascarenhas et al. (2011) Blood. 118(Suppl. 1); and Rambaldi et al.(2011) Blood 118(Suppl. 1)]. It has been reported that treatment withpracinostat results in a reduction in spleen size in 27% of patients,and IWG criteria anemia responses in approximately 10% of MF patients.Panobinostat in doses of 20, 25 and 30 mg three times daily alsodemonstrated encouraging activity in results from a phase 1/2 trial.Durable (>6 months) responses in splenomegaly, decreases inleukoerythroblastosis, and responses in anemia were reported by IWGcriteria. Givinostat also shows promise based on results of a randomizedphase 2 trial in patients with PV that did not respond to hydroxyurea. Acomplete or partial response was observed in approximately 50% ofpatients, and the combination was generally well tolerated.

In certain aspects, the present disclosure provides methods fortreating, preventing, or reducing the progression rate and/or severityof a myeloproliferative disorder (e.g., primary myelofibrosis,polycythemia vera, masked polycythemia, essential thrombocythemia,post-polycythemia vera myelofibrosis, and post-essential thrombocythemiamyelofibrosis) or one or more complications of a myeloproliferativedisorder comprising administering to a patient in need thereof aneffective amount of a TβRII antagonist (e.g., a TβRII polypeptidecomprising, consisting essential of, or consisting of an amino acidsequence that is at least 85%, 90%, 91%, 92%, 93%, 94% 95%, 96%, 97%,98%, 99%, or 100% identical to the amino acid sequence of any one of SEQID NOs: 5-17, 25, 27, 29, 31, 33, 35, 37, 39, 41, 43, 47-49, 53-62, 101,and 103-105) in combination with one or more histone deacetylaseinhibitors. Histone deacetylase inhibitors that may be used inaccordance with the methods of the disclosure include, for example,givinostat, panobinostat, and pracinostat.

The present disclosure contemplates the use of TβRII antagonists incombination with one or more therapies for treating fibrotic disorders.For example, TβRII antagonist can be administered in combination with(i.e., together with) cytotoxins, immunosuppressive agents, radiotoxicagents, and/or therapeutic antibodies. Particular co-therapeuticscontemplated by the present invention include, but are not limited to,steroids (e.g., corticosteroids, such as Prednisone), immune-suppressingand/or anti-inflammatory agents (e.g., gamma-interferon,cyclophosphamide, azathioprine, methotrexate, penicillamine,cyclosporine, colchicine, antithymocyte globulin, mycophenolate mofetil,and hydroxychloroquine), cytotoxic drugs, calcium channel blockers(e.g., nifedipine), angiotensin converting enzyme inhibitors (ACE)inhibitors, para-aminobenzoic acid (PABA), dimethyl sulfoxide,transforming growth factor beta (TGFβ) inhibitors, interleukin-5 (IL-5)inhibitors, and pan caspase inhibitors. Additional anti-fibrotic agentsthat may be used in combination with TβRII antagonist include, but arenot limited to, lectins (as described in, for example, U.S. Pat. No.7,026,283, the entire contents of which is incorporated herein byreference), as well as the anti-fibrotic agents described by Wynn et al(2007, J Clin Invest 117:524-529, the entire contents of which isincorporated herein by reference). For example, additional anti-fibroticagents and therapies include, but are not limited to, variousanti-inflammatory/immunosuppressive/cytotoxic drugs (includingcolchicine, azathioprine, cyclophosphamide, prednisone, thalidomide,pentoxifylline and theophylline), TGFβ signaling modifiers (includingrelaxin, SMAD7, HGF, and BMP7, as well as TGFβ1, TβRI, TβRII, EGR-I, andCTGF inhibitors), cytokine and cytokine receptor antagonists (inhibitorsof IL-10, IL-5, IL-6, IL-13, IL-21, IL-4R, IL-13RαI, GM-CSF, TNF-α,oncostatin M, WlSP-I, and PDGFs), cytokines and chemokincs (IFN-γ,IFN-α/β, IL-12, IL-10, HGF, CXCL10, and CXCL11), chemokine antagonists(inhibitors of CXCL1, CXCL2, CXCL12, CCL2, CCL3, CCL6, CCL17, andCCL18), chemokine receptor antagonists (inhibitors of CCR2, CCR3, CCR5,CCR7, CXCR2, and CXCR4), TLR antagonists (inhibitors of TLR3, TLR4, andTLR9), angiogenesis antagonists (VEGF-specific antibodies and adenosinedeaminase replacement therapy), antihypertensive drugs (beta blockersand inhibitors of ANG 11, ACE, and aldosterone), vasoactive substances(ET-1 receptor antagonists and bosetan), inhibitors of the enzymes thatsynthesize and process collagen (inhibitors of prolyl hydroxylase), Bcell antagonists (rituximab), integrin/adhesion molecule antagonists(molecules that block αlβl and αvβ6 integrins, as well as inhibitors ofintegrin-linked kinase, and antibodies specific for ICAM-I and VCAM-I),proapoptotic drugs that target myofibroblasts, MMP inhibitors(inhibitors of MMP2, MMP9, and MMP12), and TlMP inhibitors (antibodiesspecific for TIMP-1).

In certain embodiments, the subject methods may be used in combinationwith other conventional anti-cancer therapeutic approaches directed totreatment or prevention of proliferative disorders (e.g., tumor). Forexample, such methods can be used in prophylactic cancer prevention,prevention of cancer recurrence and metastases after surgery, and as anadjuvant of other conventional cancer therapy. The present disclosurerecognizes that the effectiveness of conventional cancer therapies(e.g., chemotherapy, radiation therapy, phototherapy, immunotherapy, andsurgery) can be enhanced through the use of a subject antagonisttherapeutic agent.

When a therapeutic agent disclosed herein is administered in combinationwith another conventional anti-neoplastic agent, either concomitantly orsequentially, such therapeutic agent may enhance the therapeutic effectof the anti-neoplastic agent or overcome cellular resistance to suchanti-neoplastic agent. This allows decrease of dosage of ananti-neoplastic agent, thereby reducing the undesirable side effects, orrestores the effectiveness of an anti-neoplastic agent in resistantcells. According to the present disclosure, the TβRII antagonistsdescribed herein may be used in combination with other compositions andprocedures for the treatment of diseases. For example, a tumor may betreated conventionally with surgery, radiation or chemotherapy combinedwith the TβRII antagonist, and then the TβRII antagonist may besubsequently administered to the patient to extend the dormancy ofmicrometastases and to stabilize any residual primary tumor.

In certain aspects of the invention, other therapeutic agents useful forcombination therapy with a TβRII antagonist and one or more cancertherapies: e.g., surgery, cytotoxic agents, radiological treatmentsinvolving irradiation or administration of radioactive substances,chemotherapeutic agents, anti-hormonal agents, growth inhibitory agents,anti-neoplastic compositions, and treatment with anti-cancer agentslisted herein and known in the art, or combinations thereof.

The term “cytotoxic agent” as used herein refers to a substance thatinhibits or prevents the function of cells and/or causes destruction ofcells. The term is intended to include radioactive isotopes (e.g.,At211, 1131, 1125, Y90, Re186, Re188, Sm153, Bi212, P32 and radioactiveisotopes of Lu), chemotherapeutic agents e.g. methotrexate, adriamicin,vinca alkaloids (vincristine, vinblastine, etoposide), doxorubicin,melphalan, mitomycin C, chlorambucil, daunorubicin or otherintercalating agents, enzymes and fragments thereof such as nucleolyticenzymes, antibiotics, and toxins such as small molecule toxins orenzymatically active toxins of bacterial, fungal, plant or animalorigin, including fragments and/or variants thereof, and the variousantitumor or anticancer agents disclosed below. Other cytotoxic agentsare described below. A tumoricidal agent causes destruction of tumorcells.

A “chemotherapeutic agent” is a chemical compound useful in thetreatment of cancer. Examples of chemotherapeutic agents includealkylating agents such as thiotepa and CYTOXAN® cyclosphosphamide; alkylsulfonates such as busulfan, improsulfan and piposulfan; aziridines suchas benzodopa, carboquone, meturedopa, and uredopa; ethylenimines andmethylamelamines including altretamine, triethylenemelamine,trietylenephosphoramide, triethiylenethiophosphoramide andtrimethylolomelamine; acetogenins (especially bullatacin andbullatacinone); delta-9-tetrahydrocannabinol (dronabinol, MARINOL®);beta-lapachone; lapachol; colchicines; betulinic acid; a camptothecin(including the synthetic analogue topotecan (HYCAMTIN®), CPT-11(irinotecan, CAMPTOSAR®), acetylcamptothecin, scopolectin, and9-aminocamptothecin); bryostatin; callystatin; CC-1065 (including itsadozelesin, carzelesin and bizelesin synthetic analogues);podophyllotoxin; podophyllinic acid; teniposide; cryptophycins(particularly cryptophycin 1 and cryptophycin 8); dolastatin;duocarmycin (including the synthetic analogues, KW-2189 and CB1-TM1);eleutherobin; pancratistatin; a sarcodictyin; spongistatin; nitrogenmustards such as chlorambucil, chlornaphazine, cyclophosphamide,estramustine, ifosfamide, mechlorethamine, mechlorethamine oxidehydrochloride, melphalan, novembichin, phenesterine, prednimustine,trofosfamide, uracil mustard; nitrosureas such as carmustine,chlorozotocin, fotemustine, lomustine, nimustine, and ranimnustine;antibiotics such as the enediyne antibiotics (e.g., calicheamicin,especially calicheamicin gammall and calicheamicin omegall (see, e.g.,Agnew, Chem Intl. Ed. Engl., 33: 183-186 (1994)); dynemicin, includingdynemicin A; an esperamicin; as well as neocarzinostatin chromophore andrelated chromoprotein enediyne antiobiotic chromophores),aclacinomysins, actinomycin, authramycin, azaserine, bleomycins,cactinomycin, carabicin, carminomycin, carzinophilin, chromomycinis,dactinomycin, daunorubicin, detorubicin, 6-diazo-5-oxo-L-norleucine,ADRIAMYCIN® doxorubicin (including morpholino-doxorubicin,cyanomorpholino-doxorubicin, 2-pyrrolino-doxorubicin anddeoxydoxorubicin), epirubicin, esorubicin, idarubicin, marcellomycin,mitomycins such as mitomycin C, mycophenolic acid, nogalamycin,olivomycins, peplomycin, porfiromycin, puromycin, quelamycin,rodorubicin, streptonigrin, streptozocin, tubercidin, ubenimex,zinostatin, zorubicin; anti-metabolites such as methotrexate and5-fluorouracil (5-FU); folic acid analogues such as denopterin,methotrexate, pteropterin, trimetrexate; purine analogs such asfludarabine, 6-mercaptopurine, thiamiprine, thioguanine; pyrimidineanalogs such as ancitabine, azacitidine, 6-azauridine, carmofur,cytarabine, dideoxyuridine, doxifluridine, enocitabine, floxuridine;androgens such as calusterone, dromostanolone propionate, epitiostanol,mepitiostane, testolactone; anti-adrenals such as aminoglutethimide,mitotane, trilostane; folic acid replenisher such as folinic acid;aceglatone; aldophosphamide glycoside; aminolevulinic acid; eniluracil;amsacrine; bestrabucil; bisantrene; edatraxate; demecolcine; diaziquone;elfornithine; elliptinium acetate; an epothilone; etoglucid; galliumnitrate; hydroxyurea; lentinan; lonidamine; maytansinoids such asmaytansine and ansamitocins; mitoguazone; mitoxantrone; mopidanmol;nitraerine; pentostatin; phenamet; pirarubicin; losoxantrone;2-ethylhydrazide; procarbazine; PSK® polysaccharide complex (JHS NaturalProducts, Eugene, Oreg.); razoxane; rhizoxin; sizofiran; spirogermanium;tenuazonic acid; triaziquone; 2,2′,2″-trichlorotriethylamine;trichothecenes (especially T-2 toxin, verracurin A, roridin A andanguidine); urethan; vindesine (ELDISINE®, FILDESIN®); dacarbazine;mannomustine; mitobronitol; mitolactol; pipobroman; gacytosine;arabinoside (“Ara-C”); thiotepa; taxoids, e.g., TAXOL® paclitaxel(Bristol-Myers Squibb Oncology, Princeton, N.J.), ABRAXANE™Cremophor-free, albumin-engineered nanoparticle formulation ofpaclitaxel (American Pharmaceutical Partners, Schaumberg, Ill.), andTAXOTERE® doxetaxel (Rhone-Poulenc Rorer, Antony, France); chlorambucil;gemcitabine (GEMZAR®); 6-thioguanine; mercaptopurine; methotrexate;platinum analogs such as cisplatin and carboplatin; vinblastine(VELBAN®); platinum; etoposide (VP-16); ifosfamide; mitoxantrone;vincristine (ONCOVIN®); oxaliplatin; leucovovin; vinorelbine(NAVELBINE®); novantrone; edatrexate; daunomycin; aminopterin;ibandronate; topoisomerase inhibitor RFS 2000; difluoromethylornithine(DMFO); retinoids such as retinoic acid; capecitabine (XELODA®);pharmaceutically acceptable salts, acids or derivatives of any of theabove; as well as combinations of two or more of the above such as CHOP,an abbreviation for a combined therapy of cyclophosphamide, doxorubicin,vincristine, and prednisolone, and FOLFOX, an abbreviation for atreatment regimen with oxaliplatin (ELOXATIN™) combined with 5-FU andleucovovin.

Also included in this definition are anti-hormonal agents that act toregulate, reduce, block, or inhibit the effects of hormones that canpromote the growth of cancer, and are often in the form of systemic, orwhole-body treatment. They may be hormones themselves. Examples includeanti-estrogens and selective estrogen receptor modulators (SERMs),including, for example, tamoxifen (including NOLVADEX® tamoxifen),EVISTA® raloxifene, droloxifene, 4-hydroxytamoxifen, trioxifene,keoxifene, LY1 17018, onapristone, and FARESTON® toremifene;anti-progesterones; estrogen receptor down-regulators (ERDs); agentsthat function to suppress or shut down the ovaries, for example,luteinizing hormone-releasing hormone (LHRH) agonists such as LUPRON®and ELIGARD® leuprolide acetate, goserelin acetate, buserelin acetateand tripterelin; other anti-androgens such as flutamide, nilutamide andbicalutamide; and aromatase inhibitors that inhibit the enzymearomatase, which regulates estrogen production in the adrenal glands,such as, for example, 4(5)-imidazoles, aminoglutethimide, MEGASE®megestrol acetate, AROMASIN® exemestane, formestane, fadrozole, RIVISOR® vorozole, FEMARA® letrozole, and ARIMIDEX® anastrozole. In addition,such definition of chemotherapeutic agents includes bisphosphonates suchas clodronate (for example, BONEFOS® or OSTAC®), DIDROC AL® etidronate,NE-58095, ZOMET A® zoledronic acid/zoledronate, FOSAMAX® alendronate,AREDIA® pamidronate, SKELID® tiludronate, or ACTONEL® risedronate; aswell as troxacitabine (a 1,3-dioxolane nucleoside cytosine analog);antisense oligonucleotides, particularly those that inhibit expressionof genes in signaling pathways implicated in aberrant cellproliferation, such as, for example, PKC-alpha, Raf, H-Ras, andepidermal growth factor receptor (EGF-R); vaccines such as THERATOPE®vaccine and gene therapy vaccines, for example, ALLOVECTIN® vaccine,LEUVECTIN® vaccine, and VAXID® vaccine; LURTOTECAN® topoisomerase 1inhibitor; ABARELIX® rmRH; lapatinib ditosylate (an ErbB-2 and EGFR dualtyrosine kinase small-molecule inhibitor also known as GW572016); andpharmaceutically acceptable salts, acids or derivatives of any of theabove.

A “growth inhibitory agent” when used herein refers to a compound orcomposition which inhibits growth of a cell either in vitro or in vivo.Thus, the growth inhibitory agent may be one which significantly reducesthe percentage of cells in S phase. Examples of growth inhibitory agentsinclude agents that block cell cycle progression (at a place other thanS phase), such as agents that induce G1 arrest and M-phase arrest.Classical M-phase blockers include the vincas (vincristine andvinblastine), taxanes, and topoisomerase II inhibitors such asdoxorubicin, epirubicin, daunorubicin, etoposide, and bleomycin. Thoseagents that arrest G1 also spill over into S-phase arrest, for example,DNA alkylating agents such as tamoxifen, prednisone, dacarbazine,mechlorethamine, cisplatin, methotrexate, 5-fluorouracil, and ara-C.Further information can be found in The Molecular Basis of Cancer,Mendelsohn and Israel, eds., Chapter 1, entitled “Cell cycle regulation,oncogenes, and antineoplastic drugs” by Murakami et al. (WB Saunders:Philadelphia, 1995), especially p. 13. The taxanes (paclitaxel anddocetaxel) are anticancer drugs both derived from the yew tree.Docetaxel (TAXOTERE®, Rhone-Poulenc Rorer), derived from the Europeanyew, is a semisynthetic analogue of paclitaxel (TAXOL®, Bristol-MyersSquibb). Paclitaxel and docetaxel promote the assembly of microtubulesfrom tubulin dimers and stabilize microtubules by preventingdepolymerization, which results in the inhibition of mitosis in cells.

7. Pharmaceutical Compositions

The therapeutic agents described herein (e.g., a TβRII polypeptidecomprising, consisting essential of, or consisting of the amino acidsequence of any one of SEQ ID NOs: 7-17, 25, 27, 29, 31, 33, 35, 37, 39,41, 43, 47-50, 52-62, 101, and 103-105) may be formulated intopharmaceutical compositions. Pharmaceutical compositions for use inaccordance with the present disclosure may be formulated in conventionalmanner using one or more physiologically acceptable carriers orexcipients. Such formulations will generally be substantiallypyrogen-free, in compliance with most regulatory requirements.

In certain embodiments, the therapeutic method of the disclosureincludes administering the composition systemically, or locally as animplant or device. When administered, the therapeutic composition foruse in this disclosure is in a pyrogen-free, physiologically acceptableform. Therapeutically useful agents other than the TβRII signalingantagonists which may also optionally be included in the composition asdescribed above, may be administered simultaneously or sequentially withthe subject compounds (e.g., TβRII polypeptides) in the methodsdisclosed herein.

Typically, protein therapeutic agents disclosed herein will beadministered parentally, and particularly intravenously orsubcutaneously. Pharmaceutical compositions suitable for parenteraladministration may comprise one or more TβRII antagonist in combinationwith one or more pharmaceutically acceptable sterile isotonic aqueous ornonaqueous solutions, dispersions, suspensions or emulsions, or sterilepowders which may be reconstituted into sterile injectable solutions ordispersions just prior to use, which may contain antioxidants, buffers,bacteriostats, solutes which render the formulation isotonic with theblood of the intended recipient or suspending or thickening agents.Examples of suitable aqueous and nonaqueous carriers which may beemployed in the pharmaceutical compositions of the disclosure includewater, ethanol, polyols (such as glycerol, propylene glycol,polyethylene glycol, and the like), and suitable mixtures thereof,vegetable oils, such as olive oil, and injectable organic esters, suchas ethyl oleate. Proper fluidity can be maintained, for example, by theuse of coating materials, such as lecithin, by the maintenance of therequired particle size in the case of dispersions, and by the use ofsurfactants.

The compositions and formulations may, if desired, be presented in apack or dispenser device which may contain one or more unit dosage formscontaining the active ingredient. The pack may for example comprisemetal or plastic foil, such as a blister pack. The pack or dispenserdevice may be accompanied by instructions for administration

Further, the composition may be encapsulated or injected in a form fordelivery to a target tissue site. In certain embodiments, compositionsof the present invention may include a matrix capable of delivering oneor more therapeutic compounds (e.g., TβRII polypeptides) to a targettissue site, providing a structure for the developing tissue andoptimally capable of being resorbed into the body. For example, thematrix may provide slow release of the TβRII antagonist. Such matricesmay be formed of materials presently in use for other implanted medicalapplications.

The choice of matrix material is based on biocompatibility,biodegradability, mechanical properties, cosmetic appearance andinterface properties. The particular application of the subjectcompositions will define the appropriate formulation. Potential matricesfor the compositions may be biodegradable and chemically defined calciumsulfate, tricalcium phosphate, hydroxyapatite, polylactic acid andpolyanhydrides. Other potential materials are biodegradable andbiologically well defined, such as bone or dermal collagen. Furthermatrices are comprised of pure proteins or extracellular matrixcomponents. Other potential matrices are non-biodegradable andchemically defined, such as sintered hydroxyapatite, bioglass,aluminates, or other ceramics. Matrices may be comprised of combinationsof any of the above mentioned types of material, such as polylactic acidand hydroxyapatite or collagen and tricalcium phosphate. The bioceramicsmay be altered in composition, such as in calcium-aluminate-phosphateand processing to alter pore size, particle size, particle shape, andbiodegradability.

In certain embodiments, methods of the invention can be administered fororally, e.g., in the form of capsules, cachets, pills, tablets, lozenges(using a flavored basis, usually sucrose and acacia or tragacanth),powders, granules, or as a solution or a suspension in an aqueous ornon-aqueous liquid, or as an oil-in-water or water-in-oil liquidemulsion, or as an elixir or syrup, or as pastilles (using an inertbase, such as gelatin and glycerin, or sucrose and acacia) and/or asmouth washes and the like, each containing a predetermined amount of anagent as an active ingredient. An agent may also be administered as abolus, electuary or paste.

In solid dosage forms for oral administration (capsules, tablets, pills,dragees, powders, granules, and the like), one or more therapeuticcompounds of the present invention may be mixed with one or morepharmaceutically acceptable carriers, such as sodium citrate ordicalcium phosphate, and/or any of the following: (1) fillers orextenders, such as starches, lactose, sucrose, glucose, mannitol, and/orsilicic acid; (2) binders, such as, for example, carboxymethylcellulose,alginates, gelatin, polyvinyl pyrrolidone, sucrose, and/or acacia; (3)humectants, such as glycerol; (4) disintegrating agents, such asagar-agar, calcium carbonate, potato or tapioca starch, alginic acid,certain silicates, and sodium carbonate; (5) solution retarding agents,such as paraffin; (6) absorption accelerators, such as quaternaryammonium compounds; (7) wetting agents, such as, for example, cetylalcohol and glycerol monostearate; (8) absorbents, such as kaolin andbentonite clay; (9) lubricants, such a talc, calcium stearate, magnesiumstearate, solid polyethylene glycols, sodium lauryl sulfate, andmixtures thereof; and (10) coloring agents. In the case of capsules,tablets and pills, the pharmaceutical compositions may also comprisebuffering agents. Solid compositions of a similar type may also beemployed as fillers in soft and hard-filled gelatin capsules using suchexcipients as lactose or milk sugars, as well as high molecular weightpolyethylene glycols and the like.

Liquid dosage forms for oral administration include pharmaceuticallyacceptable emulsions, microemulsions, solutions, suspensions, syrups,and elixirs. In addition to the active ingredient, the liquid dosageforms may contain inert diluents commonly used in the art, such as wateror other solvents, solubilizing agents and emulsifiers, such as ethylalcohol, isopropyl alcohol, ethyl carbonate, ethyl acetate, benzylalcohol, benzyl benzoate, propylene glycol, 1,3-butylene glycol, oils(in particular, cottonseed, groundnut, corn, germ, olive, castor, andsesame oils), glycerol, tetrahydrofuryl alcohol, polyethylene glycolsand fatty acid esters of sorbitan, and mixtures thereof. Besides inertdiluents, the oral compositions can also include adjuvants such aswetting agents, emulsifying and suspending agents, sweetening,flavoring, coloring, perfuming, and preservative agents.

Suspensions, in addition to the active compounds, may contain suspendingagents such as ethoxylated isostearyl alcohols, polyoxyethylenesorbitol, and sorbitan esters, microcrystalline cellulose, aluminummetahydroxide, bentonite, agar-agar and tragacanth, and mixturesthereof.

The compositions of the invention may also contain adjuvants, such aspreservatives, wetting agents, emulsifying agents and dispersing agents.Prevention of the action of microorganisms may be ensured by theinclusion of various antibacterial and antifungal agents, for example,paraben, chlorobutanol, phenol sorbic acid, and the like. It may also bedesirable to include isotonic agents, such as sugars, sodium chloride,and the like into the compositions. In addition, prolonged absorption ofthe injectable pharmaceutical form may be brought about by the inclusionof agents which delay absorption, such as aluminum monostearate andgelatin.

It is understood that the dosage regimen will be determined by theattending physician considering various factors which modify the actionof the subject compounds of the invention (e.g., TβRII polypeptides).The various factors include, but are not limited to, the patient's age,sex, and diet, the severity disease, time of administration, and otherclinical factors. Optionally, the dosage may vary with the type ofmatrix used in the reconstitution and the types of compounds in thecomposition. The addition of other known growth factors to the finalcomposition, may also affect the dosage. Progress can be monitored byperiodic assessment of bone growth and/or repair, for example, X-rays(including DEXA), histomorphometric determinations, and tetracyclinelabeling.

In certain embodiments, the present invention also provides gene therapyfor the in vivo production of TβRII antagonist. Such therapy wouldachieve its therapeutic effect by introduction of the TβRIIpolynucleotide sequences into cells or tissues having the disorders aslisted above. Delivery of TβRII polynucleotide sequences can be achievedusing a recombinant expression vector such as a chimeric virus or acolloidal dispersion system. Preferred for therapeutic delivery of TβRIIpolynucleotide sequences is the use of targeted liposomes.

Various viral vectors which can be utilized for gene therapy as taughtherein include adenovirus, herpes virus, vaccinia, or, preferably, anRNA virus such as a retrovirus. Preferably, the retroviral vector is aderivative of a murine or avian retrovirus. Examples of retroviralvectors in which a single foreign gene can be inserted include, but arenot limited to: Moloney murine leukemia virus (MoMuLV), Harvey murinesarcoma virus (HaMuSV), murine mammary tumor virus (MuMTV), and RousSarcoma Virus (RSV). A number of additional retroviral vectors canincorporate multiple genes. All of these vectors can transfer orincorporate a gene for a selectable marker so that transduced cells canbe identified and generated. Retroviral vectors can be madetarget-specific by attaching, for example, a sugar, a glycolipid, or aprotein. Preferred targeting is accomplished by using an antibody. Thoseof skill in the art will recognize that specific polynucleotidesequences can be inserted into the retroviral genome or attached to aviral envelope to allow target specific delivery of the retroviralvector containing the TβRII polynucleotide. In a preferred embodiment,the vector is targeted to bone or cartilage.

Alternatively, tissue culture cells can be directly transfected withplasmids encoding the retroviral structural genes gag, pol and env, byconventional calcium phosphate transfection. These cells are thentransfected with the vector plasmid containing the genes of interest.The resulting cells release the retroviral vector into the culturemedium.

Another targeted delivery system for TβRII antagonist polynucleotides isa colloidal dispersion system. Colloidal dispersion systems includemacromolecule complexes, nanocapsules, microspheres, beads, andlipid-based systems including oil-in-water emulsions, micelles, mixedmicelles, and liposomes. The preferred colloidal system of thisinvention is a liposome. Liposomes are artificial membrane vesicleswhich are useful as delivery vehicles in vitro and in vivo. RNA, DNA andintact virions can be encapsulated within the aqueous interior and bedelivered to cells in a biologically active form (see e.g., Fraley, etal., Trends Biochem. Sci., 6:77, 1981). Methods for efficient genetransfer using a liposome vehicle, are known in the art, see e.g.,Mannino, et al., Biotechniques, 6:682, 1988. The composition of theliposome is usually a combination of phospholipids, usually incombination with steroids, especially cholesterol. Other phospholipidsor other lipids may also be used. The physical characteristics ofliposomes depend on pH, ionic strength, and the presence of divalentcations.

Examples of lipids useful in liposome production include phosphatidylcompounds, such as phosphatidylglycerol, phosphatidylcholine,phosphatidylserine, phosphatidylethanolamine, sphingolipids,cerebrosides, and gangliosides. Illustrative phospholipids include eggphosphatidylcholine, dipalmitoylphosphatidylcholine, anddistearoylphosphatidylcholine. The targeting of liposomes is alsopossible based on, for example, organ-specificity, cell-specificity, andorganelle-specificity and is known in the art.

The disclosure provides formulations that may be varied to include acidsand bases to adjust the pH; and buffering agents to keep the pH within anarrow range.

EXEMPLIFICATION

The invention now being generally described, it will be more readilyunderstood by reference to the following examples, which are includedmerely for purposes of illustration of certain embodiments of thepresent invention, and are not intended to limit the invention.

Example 1 Generation of Receptor Fusion Protein Variants TβRII ECDVariants

Human TβRII occurs naturally in at least two isoforms A (long) and B(short) generated by alternative splicing in the extracellular domain(ECD) (FIGS. 1 and 2). TβRII binds with high affinity to TGFβ1 andTGFβ3. While in some therapeutic settings this spectrum of ligandbinding may be advantageous, in other settings a more selective moleculemay be superior. As detailed below, Applicants generated and haveenvisioned various TβRII polypeptides and Fc fusion proteins comprisingan extracellular domain of the TβRII long or short isoforms(TβRII_(long) or TβRII_(short)) as well as variants thereof.

The wild-type hTβRII_(long)(23-184) sequence is shown below (SEQ ID NO:13), in which the 25 amino-acid insertion is underlined. Note thatsplicing results in a conservative amino acid substitution (Val→Ile) atthe flanking position C-terminal to the insertion. Sequencerelationships among several hTβRII_(short) variants and theirhTβRII_(long) counterparts are indicated in FIG. 3.

(SEQ ID NO: 13) 1 TIPPHVQKSD VEMEAQKDEI ICPSCNRTAH PLRHINNDMI VTDNNGAVKF51 PQLCKFCDVR FSTCDNQKSC MSNCSITSIC EKPQEVCVAV WRKNDENITL 101 ETVCHDPKLPYHDFILEDAA SPKCIMKEKK KPGETFFMCS CSSDECNDNI 151 IFSEEYNTSN PD

Applicant generated a hTβRII_(long)(23-184)-Fc fusion protein in whichthe hTβRII_(long)(23-184) domain was fused at the C-terminus (via aminimal linker) to a human IgG1 Fc domain and fused at the N-terminus toa TPA leader sequence, which has the following amino acid sequence (SEQID NO: 101):

(SEQ ID NO: 101) 1 MDAMKRGLCC VLLLCGAVFV SPGATIPPHV QKSDVEMEAQKDEIICPSCN 51 RTAHPLRHIN NDMIVTDNNG AVKFPQLCKF CDVRFSTCDN QKSCMSNCSI 101TSICEKPQEV CVAVWRKNDE NITLETVCHD PKLPYHDFIL EDAASPKCIM 151 KEKKKPGETFFMCSCSSDEC NDNIIFSEEY NTSNPDTGGG THTCPPCPAP 201ELLGGPSVFL FPPKPKDTLM ISRTPEVTCV VVDVSHEDPE VKFNWYVDGV 251EVHNAKTKPR EEQYNSTYRV VSVLTVLHQD WLNGKEYKCK VSNKALPAPI 301EKTISKAKGQ PREPQVYTLP PSREEMTKNQ VSLTCLVKGF YPSDIAVEWE 351SNGQPENNYK TTPPVLDSDG SFFLYSKLTV DKSRWQQGNV FSCSVMHEAL 401HNHYTQKSLS LSPGKThe N-terminal leader sequence and C-terminal Fc domain are representedby a single underline and the linker domain is indicated by doubleunderline. A nucleotide sequence encoding the hTβRII_(long)(23-184)-Fcfusion protein has the following nucleotide sequence (SEQ ID NO: 102):

(SEQ ID NO: 102) 1 ATGGATGCAA TGAAGAGAGG GCTCTGCTGT GTGCTGCTGCTGTGTGGAGC AGTCTTCGTT 61 TCGCCCGGCG CCACGATCCC ACCGCACGTT CAGAAGTCGGATGTGGAAAT GGAGGCCCAG 121 AAAGATGAAA TCATCTGCCC CAGCTGTAAT AGGACTGCCCATCCACTGAG ACATATTAAT 181 AACGACATGA TAGTCACTGA CAACAACGGT GCAGTCAAGTTTCCACAACT GTGTAAATTT 241 TGTGATGTGA GATTTTCCAC CTGTGACAAC CAGAAATCCTGCATGAGCAA CTGCAGCATC 301 ACCTCCATCT GTGAGAAGCC ACAGGAAGTC TGTGTGGCTGTATGGAGAAA GAATGACGAG 361 AACATAACAC TAGAGACAGT TTGCCATGAC CCCAAGCTCCCCTACCATGA CTTTATTCTG 421 GAAGATGCTG CTTCTCCAAA GTGCATTATG AAGGAAAAAAAAAAGCCTGG TGAGACTTTC 481 TTCATGTGTT CCTGTAGCTC TGATGAGTGC AATGACAACATCATCTTCTC AGAAGAATAT 541 AACACCAGCA ATCCTGACAC CGGTGGTGGA ACTCACACATGCCCACCGTG CCCAGCACCT 601 GAACTCCTGG GGGGACCGTC AGTCTTCCTC TTCCCCCCAAAACCCAAGGA CACCCTCATG 661 ATCTCCCGGA CCCCTGAGGT CACATGCGTG GTGGTGGACGTGAGCCACGA AGACCCTGAG 721 GTCAAGTTCA ACTGGTACGT GGACGGCGTG GAGGTGCATAATGCCAAGAC AAAGCCGCGG 781 GAGGAGCAGT ACAACAGCAC GTACCGTGTG GTCAGCGTCCTCACCGTCCT GCACCAGGAC 841 TGGCTGAATG GCAAGGAGTA CAAGTGCAAG GTCTCCAACAAAGCCCTCCC AGCCCCCATC 901 GAGAAAACCA TCTCCAAAGC CAAAGGGCAG CCCCGAGAACCACAGGTGTA CACCCTGCCC 961 CCATCCCGGG AGGAGATGAC CAAGAACCAG GTCAGCCTGACCTGCCTGGT CAAAGGCTTC 1021 TATCCCAGCG ACATCGCCGT GGAGTGGGAG AGCAATGGGCAGCCGGAGAA CAACTACAAG 1081 ACCACGCCTC CCGTGCTGGA CTCCGACGGC TCCTTCTTCCTCTATAGCAA GCTCACCGTG 1141 GACAAGAGCA GGTGGCAGCA GGGGAACGTC TTCTCATGCTCCGTGATGCA TGAGGCTCTG 1201 CACAACCACT ACACGCAGAA GAGCCTCTCC CTGTCTCCGGGTAAATGAA processed version of the hTβRII_(long)(23-184)-Fc fusion protein hasthe following amino acid sequence (SEQ ID NO: 103):

(SEQ ID NO: 103) TIPPHV QKSDVEMEAQ KDEIICPSCN RTAHPLRHIN NDMIVTDNNGAVKFPQLCKF CDVRFSTCDN QKSCMSNCSI TSICEKPQEV CVAVWRKNDE NITLETVCHDPKLPYHDFIL EDAASPKCIM KEKKKPGETF FMCSCSSDEC NDNIIFSEEYNTSNPDTGGG THTCPPCPAP ELLGGPSVFLFPPKPKDTLM ISRTPEVTCV VVDVSHEDPE VKFNWYVDGVEVHNAKTKPR EEQYNSTYRV VSVLTVLHQD WLNGKEYKCKVSNKALPAPI EKTISKAKGQ PREPQVYTLP PSREEMTKNQVSLTCLVKGF YPSDIAVEWE SNGQPENNYK TTPPVLDSDGSFFLYSKLTV DKSRWQQGNV FSCSVMHEAL HNHYTQKSLS LSPGK

For use in certain animal models described herein, Applicants generatedan Fc fusion protein comprising the mature, full-length ECD from themouse TβRII isoform 1, which is designated herein as mTβRII-Fc. Themouse TβRII isoform 1 is homologous to the human TβRII isoform A (longform) and thus is a mouse equivalent version of thehTβRII_(long)(23-184)-Fc fusion protein above described. As with thehuman version, it was determined that mTβRII-Fc binds with high affinity(picomolar) to TGFβ1 and TGFβ3, but does not bind to TGFβ2. In addition,it was determined that the hTβRII_(long)(23-184)-Fc fusion protein andmTβRII-Fc are potent inhibitors of TGFβ1 and TGFβ3 activity, but doesnot inhibit TGFβ2 activity, in a cell-based assay as described below.

Applicants also envision five corresponding variants (SEQ ID NO: 14-17)based on the wild-type hTβRII_(long)(23-184) sequence shown in (SEQ IDNO: 13) and Fc fusion proteins thereof.

(1) The hTβRII_(long)(23-184/D135K) amino acid sequence shown below (SEQID NO: 14), in which the substituted residue is double underlined.

(SEQ ID NO: 14) 1 TIPPHVQKSD VEMEAQKDEI ICPSCNRTAH PLRHINNDMI VTDNNGAVKF51 PQLCKFCDVR FSTCDNQKSC MSNCSITSIC EKPQEVCVAV WRKNDENITL 101ETVCHDPKLP YHKFILEDAA SPKCIMKEKK KPGETFFMCS CSSDECNDNI 151 IFSEEYNTSN PD(2) The N-terminally truncated hTβRII_(long)(29-184) amino acid sequenceshown below (SEQ ID NO: 15).

(SEQ ID NO: 15) 1 QKSDVEMEAQ KDEIICPSCN RTAHPLRHIN NDMIVTDNNG AVKFPQLCKF51 CDVRFSTCDN QKSCMSNCSI TSICEKPQEV CVAVWRKNDE NITLETVCHD 101PKLPYHDFIL EDAASPKCIM KEKKKPGETF FMCSCSSDEC NDNIIFSEEY 151 NTSNPD(3) The N-terminally truncated hTβRII_(long)(60-184) amino acid sequenceshown below (SEQ ID NO: 104).

(SEQ ID NO: 104) 1DMIVTDNNGA VKFPQLCKFC DVRFSTCDNQ KSCMSNCSIT SICEKPQEVC 51VAVWRKNDEN ITLETVCHDP KLPYHDFILE DAASPKCIMK EKKKPGETFF 101MCSCSSDECN DNIIFSEEYN TSNPD(4) The C-terminally truncated hTβRII_(long)(23-178) amino acid sequenceshown below (SEQ ID NO: 16).

(SEQ ID NO: 16) 1 TIPPHVQKSD VEMEAQKDEI ICPSCNRTAH PLRHINNDMI VTDNNGAVKF51 PQLCKFCDVR FSTCDNQKSC MSNCSITSIC EKPQEVCVAV WRKNDENITL 101ETVCHDPKLP YHDFILEDAA SPKCIMKEKK KPGETFFMCS CSSDECNDNI 151 IFSEEY(5) The C-terminally truncated hTβRII_(long)(23-178/N95D) amino acidsequence shown below (SEQ ID NO: 17), in which the substituted residueis double underlined.

(SEQ ID NO: 17) 1 TIPPHVQKSD VEMEAQKDEI ICPSCNRTAH PLRHINNDMI VTDNNGAVKF51 PQLCKFCDVR FSTCDNQKSC MSDCSITSIC EKPQEVCVAV WRKNDENITL 101ETVCHDPKLP YHDFILEDAA SPKCIMKEKK KPGETFFMCS CSSDECNDNI 151 IFSEEY

The wild-type hTβRII_(short)(23-159) sequence shown below (SEQ ID NO: 7)served as the basis for five receptor ECD variants listed below (SEQ IDNO: 8-12). A wild type hTβRII_(short)(23-159) was fused to an Fc portionof IgG2 to generate a novel, base Fc fusion construct. See SEQ ID Nos.50, 51 and 52, below.

(SEQ ID NO: 7) 1 TIPPHVQKSV NNDMIVTDNN GAVKFPQLCK FCDVRFSTCD NQKSCMSNCS51 ITSICEKPQE VCVAVWRKND ENITLETVCH DPKLPYHDFI LEDAASPKCI 101MKEKKKPGET FFMCSCSSDE CNDNIIFSEE YNTSNPD(1) The hTβRII_(short)(23-159/D110K) amino acid sequence shown below(SEQ ID NO: 8), in which the substituted residue is underlined.

(SEQ ID NO: 8) 1 TIPPHVQKSV NNDMIVTDNN GAVKFPQLCK FCDVRFSTCD NQKSCMSNCS51 ITSICEKPQE VCVAVWRKND ENITLETVCH DPKLPYHKFI LEDAASPKCI 101MKEKKKPGET FFMCSCSSDE CNDNIIFSEE YNTSNPD(2) The N-terminally truncated hTβRII_(short)(29-159) amino acidsequence shown below (SEQ ID NO: 9).

(SEQ ID NO: 9) 1 QKSVNNDMIV TDNNGAVKFP QLCKFCDVRF STCDNQKSCM SNCSITSICE51 KPQEVCVAVW RKNDENITLE TVCHDPKLPY HDFILEDAAS PKCIMKEKKK 101PGETFFMCSC SSDECNDNII FSEEYNTSNP D(3) The N-terminally truncated hTβRII_(short)(35-159) amino acidsequence shown below (SEQ ID NO: 10).

(SEQ ID NO: 10) 1 DMIVTDNNGA VKFPQLCKFC DVRFSTCDNQ KSCMSNCSIT SICEKPQEVC51 VAVWRKNDEN ITLETVCHDP KLPYHDFILE DAASPKCIMK EKKKPGETFF 101MCSCSSDECN DNIIFSEEYN TSNPD(4) The C-terminally truncated hTβRII_(short)(23-153) amino acidsequence shown below (SEQ ID NO: 11).

(SEQ ID NO: 11) 1 TIPPHVQKSV NNDMIVTDNN GAVKFPQLCK FCDVRFSTCD NQKSCMSNCS51 ITSICEKPQE VCVAVWRKND ENITLETVCH DPKLPYHDFI LEDAASPKCI 101MKEKKKPGET FFMCSCSSDE CNDNIIFSEE Y(5) The C-terminally truncated hTβRII_(short)(23-153/N70D) amino acidsequence shown below (SEQ ID NO: 12), in which the substituted residueis underlined.

(SEQ ID NO: 12) 1 TIPPHVQKSV NNDMIVTDNN GAVKFPQLCK FCDVRFSTCD NQKSCMSDCS51 ITSICEKPQE VCVAVWRKND ENITLETVCH DPKLPYHDFI LEDAASPKCI 101MKEKKKPGET FFMCSCSSDE CNDNIIFSEE Y

Additional TβRII ECD variants include:

(A) The N- and C-terminally truncated hTβRII_(short)(35-153) orhTβRII_(long)(60-178) amino acid sequence shown below (SEQ ID NO: 47).

(SEQ ID NO: 47) 1 DMIVTDNNGA VKFPQLCKFC DVRFSTCDNQ KSCMSNCSIT SICEKPQEVC51 VAVWRKNDEN ITLETVCHDP KLPYHDFILE DAASPKCIMK EKKKPGETFF 101MCSCSSDECN DNIIFSEEY(B) The N- and C-terminally truncated hTβRII_(short)(29-153) amino acidsequence shown below (SEQ ID NO: 48).

(SEQ ID NO: 48) 1 QKSVNNDMIV TDNNGAVKFP QLCKFCDVRF STCDNQKSCM SNCSITSICE51 KPQEVCVAVW RKNDENITLE TVCHDPKLPY HDFILEDAAS PKCIMKEKKK 101PGETFFMCSC SSDECNDNII FSEEY(C) The N- and C-terminally truncated hTβRII_(long)(29-178) amino acidsequence shown below (SEQ ID NO: 49).

(SEQ ID NO: 49) 1 QKSDVEMEAQ KDEIICPSCN RTAHPLRHIN NDMIVTDNNG AVKFPQLCKF51 CDVRFSTCDN QKSCMSNCSI TSICEKPQEV CVAVWRKNDE NITLETVCHD 101PKLPYHDFIL EDAASPKCIM KEKKKPGETF FMCSCSSDEC NDNIIFSEEY

Any of the above variants (e.g., SEQ ID NO: 8-12, 14-17, and 47-49)could incorporate an insertion of 36 amino acids (SEQ ID NO: 18) betweenthe pair of glutamate residues (positions 151 and 152 of SEQ ID NO: 5,or positions 176 and 177 of SEQ ID NO: 6) located near the C-terminus ofthe hTβRII ECD, as occurs naturally in the hTβRII isoform C [Konrad etal. (2007) BMC Genomics 8:318].

(SEQ ID NO: 18) GRCKIRHIGS NNRLQRSTCQ NTGWESAHVM KTPGFRAs an example, the paired glutamate residues flanking the optionalinsertion site are denoted below (underlined) for thehTβRII_(short)(29-159) variant (SEQ ID NO: 105).

(SEQ ID NO: 105) 1 QKSVNNDMIV TDNNGAVKFP QLCKFCDVRF STCDNQKSCMSNCSITSICE 51 KPQEVCVAVW RKNDENITLE TVCHDPKLPY HDFILEDAAS PKCIMKEKKK 101PGETFFMCSC SSDECNDNII FSEEYNTSNP D

In part, Applicants sought polypeptides with enhanced or reducedselectivity for TGFβ1 or TGFβ3 by generating fusion proteins comprisingvariants of human TβRII ECD. The wild-type hTβRII_(short)(23-159)sequence shown below (SEQ ID NO: 7) served as the basis for fivereceptor ECD variants listed below (SEQ ID NO: 8-12). A wild typehTβRII_(short)(23-159) was fused to an Fc portion of IgG2 to generate anovel, base Fc fusion construct. See SEQ ID Nos. 50, 51 and 52, below.

Applicants envision five corresponding variants (SEQ ID NO: 14-17) basedon the wild-type hTβRII_(long)(23-184) sequence shown below (SEQ ID NO:13), in which the 25 amino-acid insertion is underlined. Note thatsplicing results in a conservative amino acid substitution (Val→Ile) atthe flanking position C-terminal to the insertion. Sequencerelationships among several hTβRII_(short) variants and theirhTβRII_(long) counterparts are indicated in FIG. 3.

Fc Domain Variants

hTβRII-hFc fusion proteins were generated in which five hTβRII_(short)variants described above were each fused at their C-terminus (via aminimal linker) to a human IgG2 Fc domain, which has the following aminoacid sequence (SEQ ID NO: 19):

(SEQ ID NO: 19) 1 VECPPCPAPP VAGPSVFLFP PKPKDTLMIS RTPEVTCVVV DVSHEDPEVQ51 FNWYVDGVEV HNAKTKPREE QFNSTFRVVS VLTVVHQDWL NGKEYKCKVS 101 NKGLPAPIEKTISKTKGQPR EPQVYTLPPS REEMTKNQVS LTCLVKGFYP 151 SDIAVEWESN GQPENNYKTTPPMLDSDGSF FLYSKLTVDK SRWQQGNVFS 201 CSVMHEALHN HYTQKSLSLS PGK

Applicants envision hTβRII(_(short and long))-hFC fusion proteinscomprising Fc domains, including full-length human IgG2 Fc domain above,the IgG1 Fc (hG1Fc) (SEQ ID NO: 20, below) and N-terminally truncatedhuman IgG1 Fc (hG1Fc_(short)) (SEQ ID NO: 21, below). Optionally, apolypeptide unrelated to an Fc domain could be attached in place of theFc domain.

(SEQ ID NO: 20) 1 GGPKSCDKTH TCPPCPAPEL LGGPSVFLFP PKPKDTLMIS RTPEVTCVVV51 DVSHEDPEVK FNWYVDGVEV HNAKTKPREE QYNSTYRVVS VLTVLHQDWL 101 NGKEYKCKVSNKALPAPIEK TISKAKGQPR EPQVYTLPPS REEMTKNQVS 151 LTCLVKGFYP SDIAVEWESNGQPENNYKTT PPVLDSDGSF FLYSKLTVDK 201 SRWQQGNVFS CSVMHEALHN HYTQKSLSLSPGK (SEQ ID NO: 21) 1 THTCPPCPAP ELLGGPSVFL FPPKPKDTLM ISRTPEVTCVVVDVSHEDPE 51 VKFNWYVDGV EVHNAKTKPR EEQYNSTYRV VSVLTVLHQD WLNGKEYKCK 101VSNKALPAPI EKTISKAKGQ PREPQVYTLP PSREEMTKNQ VSLTCLVKGF 151 YPSDIAVEWESNGQPENNYK TTPPVLDSDG SFFLYSKLTV DKSRWQQGNV 201 FSCSVMHEAL HNHYTQKSLSLSPGK

Leader Sequence Variants

The following three leader sequences were considered:

(1) Native: (SEQ ID NO: 22) MGRGLLRGLWPLHIVLWTRIAS (2) Tissueplasminogen activator (TPA): (SEQ ID NO: 23) MDAMKRGLCCVLLLCGAVFVSP (3)Honey bee melittin (HBML): (SEQ ID NO: 24) MKFLVNVALVFMVVYISYIYAExpression of hTβRII-hFc Fusion Proteins

The selected hTβRII-hFc protein variants incorporate the TPA leader andhave the unprocessed amino-acid sequences shown in SEQ ID NOs: 25, 29,33, 37, 41, and 101 (see Example 3). Corresponding nucleotide sequencesfor these variants are SEQ ID NOs: 26, 30, 34, 38, 42, and 102. SelectedhTβRII-hFc variants, each with a G2Fc domain (SEQ ID NO: 19), wereexpressed in HEK-293 cells and purified from conditioned media byfiltration and protein A chromatography. Purity of samples for reportergene assays was evaluated by SDS-PAGE and Western blot analysis.

Applicants envision additional hTβRII-hFc protein variants with theunprocessed amino-acid sequences shown in SEQ ID NOs: 27, 31, 35, 39,43, and 101 and corresponding nucleotide sequences shown in SEQ ID NOs:28, 32, 36, 40, 44, and 101.

The amino acid sequence of the wild-type short constructhTβRII_(short)(23-159)-hG2Fc (SEQ ID NO: 50 is shown below.

(SEQ ID NO: 50) TIPPHVQKSV NNDMIVTDNN GAVKFPQLCK FCDVRFSTCD NQKSCMSNCSITSICEKPQE VCVAVWRKND ENITLETVCH DPKLPYHDFI LEDAASPKCI MKEKKKPGETFFMCSCSSDE CNDNIIFSEE YNTSNPDTGG GVECPPCPAP PVAGPSVFLF PPKPKDTLMISRTPEVTCVV VDVSHEDPEV QFNWYVDGVE VHNAKTKPRE EQFNSTFRVV SVLTVVHQDWLNGKEYKCKV SNKGLPAPIE KTISKTKGQP REPQVYTLPP SREEMTKNQV SLTCLVKGFYPSDIAVEWES NGQPENNYKT TPPMLDSDGS FFLYSKLTVD KSRWQQGNVF SCSVMHEALHNHYTQKSLSL SPGK

This protein was expressed from a construct including a TPA leadersequence, as shown below (SEQ ID NO:52). Dotted underline denotesleader, and solid underline denotes linker.

The nucleic acid sequence encoding SEQ ID NO:52 is shown below:

Example 2 Differential Ligand Inhibition by Receptor Fusion ProteinVariants in Cell-Based Assay

A reporter gene assay in A549 cells was used to determine the ability ofhTβRII-hFc variants to inhibit activity of TGFβ1, TGFβ2, and TGFβ3. Thisassay is based on a human lung carcinoma cell line transfected with apGL3(CAGA)12 reporter plasmid (Dennler et al, 1998, EMBO 17: 3091-3100)as well as a Renilla reporter plasmid (pRLCMV) to control fortransfection efficiency. The CAGA motif is present in the promoters ofTGFβ-responsive genes (for example, PAI-1), so this vector is of generaluse for factors signaling through SMAD2 and SMAD3.

On the first day of the assay, A549 cells (ATCC®: CCL-185™) weredistributed in 48-well plates at 6.5×10⁴ cells per well. On the secondday, a solution containing 10 pGL3(CAGA)12, 100 ng pRLCMV, 30 μlX-tremeGENE 9 (Roche Applied Science), and 970 μl OptiMEM (Invitrogen)was preincubated for 30 min, then added to Eagle's minimum essentialmedium (EMEM, ATCC®) supplemented with 0.1% BSA, which was applied tothe plated cells (500 μl/well) for incubation overnight at roomtemperature. On the third day, medium was removed, and cells wereincubated overnight at 37° C. with a mixture of ligands and inhibitorsprepared as described below.

Serial dilutions of test articles were made in a 48-well plate in a 200μl volume of assay buffer (EMEM+0.1% BSA). An equal volume of assaybuffer containing the test ligand was added to obtain a final ligandconcentration equal to the EC50 determined previously. Human TGFβ1,human TGFβ2, and human TGFβ3 were obtained from PeproTech. Testsolutions were incubated at 37° C. for 30 minutes, then 250 μl of themixture was added to all wells. Each concentration of test article wasdetermined in duplicate. After incubation with test solutions overnight,cells were rinsed with phosphate-buffered saline, then lysed withpassive lysis buffer (Promega E1941) and stored overnight at −70° C. Onthe fourth and final day, plates were warmed to room temperature withgentle shaking. Cell lysates were transferred in duplicate to achemiluminescence plate (96-well) and analyzed in a luminometer withreagents from a Dual-Luciferase Reporter Assay system (Promega E1980) todetermine normalized luciferase activity.

This assay was used to screen receptor fusion protein variants forpotential inhibitory effects on cell signaling by TβRII ligands.Consistent with previous reports concerning wild-type TβRII_(short)-Fcand TβRII_(long)-Fc [del Re et al. (2004) J Biol Chem 279:22765], noneof the variants tested were able to inhibit TGFβ2, even at highconcentrations. However, hTβRII-hFc variants unexpectedly showeddifferential inhibition of cellular signaling mediated by TGFβ1 andTGFβ3. Compared with wild-type TβRII_(short)(23-159)-G2Fc, theTβRII_(short)(23-159/D110K)-G2Fc variant exhibited loss of inhibition ofTGFβ1 but maintained intermediate inhibition of TGFβ3 (see table below).Position 110 is located in the “hook” region of TβRII [Radaev et al.(2010) J Biol Chem 285:14806] but has not been suggested to conferselectivity among the recognized TβRII ligands TGFβ1, TGFβ2, and TGFβ3.Thus, this variant displays a profile of differential ligand inhibitionin which some TGFβ3 inhibition is maintained the variant has little tono effect on TGFβ1 activity.

IC₅₀ (nM) hTGFβ1 hTGFβ3 Construct (640 pg/ml) (270 pg/ml) Full-lengthTβRII_(short) 1.73 0.14 wild-type ECD (23-159)-G2Fc Full-lengthTβRII_(short) ND (>73.6) ~6.9 ECD with D110K (23-159/D110K)-G2Fcsubstitution ND, not determined

In a second experiment, potencies of variants with N-terminallytruncated TβRII ECD were compared with that of full-length wild-typeTβRII ECD. As shown in the table below, TβRII_(short)(29-159)-G2Fc andTβRII_(short)(35-159)-G2Fc displayed a greatly diminished ability toinhibit TGFβ3 but maintains some TGFβ1 inhibitor effects.

IC₅₀ (nM) hTGFβ1 hTGFβ3 Construct (640 pg/ml) (270 pg/ml) Full-lengthTβRII_(short) 0.52 0.37 wild-type ECD (23-159)-G2Fc N′Δ6 ECDTβRII_(short) 2.05 ND (>7.5) (29-159)-G2Fc N′Δ12 ECD TβRII_(short) 2.51ND (>7.5) (35-159)-G2Fc ND, not determined

In a third experiment, we determined the effect on potency of a N70Dsubstitution in a C-terminally truncated TβRII ECD. This aspartateresidue represents a potential glycosylation site. As shown in the tablebelow, TβRII_(short)(23-153/N70D)-G2Fc displayed greatly diminishedability to inhibit TGFβ1 and virtually undiminished ability to inhibitTGFβ3 compared to TβRII_(short)(23-153)-G2Fc. Thus, the C-terminallytruncated variant with N70D substitution exhibits a profile ofdifferential ligand inhibition in which TGFβ3 is inhibited most potentlybut greatly diminished potency for TGFβ1 inhibition.

IC₅₀ (nM) hTGFβ1 hTGFβ3 Construct (640 pg/ml) (270 pg/ml) Full-lengthTβRII_(short) ND ND wild-type ECD (23-159)-G2Fc C′Δ6 ECD TβRII_(short)2.62 0.14 (23-153)-G2Fc C′Δ6 TβRII_(short) 17.7 0.28 ECD with N70D(23-153/N70D)-G2Fc substitution

Together, these results demonstrate that Applicants have generatedtruncations and mutations of the TβRII ECD that exhibit widely differentligand binding profiles. Activity profiles of these variants can besummarized in the following table.

Summary of Ligand Selectivity Degree of Ligand Inhibition Negli-Construct Potent Moderate gible Full-length TβRII_(short) TGFβ1 — TGFβ2wild-type ECD (23-159)-G2Fc TGFβ3 Full-length TβRII_(short) — TGFβ3TGFβ1 ECD with D110K (23-159/D110K)-G2Fc TGFβ2 substitution N′Δ6 ECDTβRII_(short) — TGFβ1 TGFβ2 (29-159)-G2Fc TGFβ3 N′Δ12 ECD TβRII_(short)— TGFβ1 TGFβ2 (35-159)-G2Fc TGFβ3 C′Δ6 TβRII_(short)(23- TGFβ3 — TGFβ1ECD with N70D 153/N70D)-G2Fc TGFβ2 substitutionWe predict that the TβRII_(long) ECD counterparts of these TβRII_(short)ECD variants will exhibit similar ligand selectivity. In addition, aC′46 truncated ECD (such as SEQ ID NOs: 11 and 16 for the TβRII_(short)and TβRII_(long) isoforms, respectively) can be used as a base sequencefor TβRII_(short) or TβRII_(long) in which to introduce mutations andN-terminal truncations.

Example 3 Exemplary hTβRII-hFc Nucleic Acids and Proteins

This example summarizes nucleic acid constructs that can be used toexpress TβRII constructs in HEK-293 or CHO cells, according to themethods provided herein in order to provide the proteins isolated fromcell culture. In each case the mature protein isolated from cell culturewill have the leader sequence (dotted underline in each sequence below)removed.

Item 1 shows the amino acid sequence ofhTβRII_(short)(23-159/D110K)-hG2Fc (SEQ ID NO: 25). Double underlineindicates D110K substitution. Dotted underline denotes leader, and solidunderline denotes linker.

(SEQ ID NO: 25)   1

 51 QLCKFCDVRF STCDNQKSCM SNCSITSICE KPQEVCVAVW RKNDENITLE 101TVCHDPKLPY HKFILEDAAS PKCIMKEKKK PGETFFMCSC SSDECNDNII 151FSEEYNTSNP DTGGGVECPP CPAPPVAGPS VFLFPPKPKD TLMISRTPEV 201TCVVVDVSHE DPEVQFNWYV DGVEVHNAKT KPREEQFNST FRVVSVLTVV 251HQDWLNGKEY KCKVSNKGLP APIEKTISKT KGQPREPQVY TLPPSREEMT 301KNQVSLTCLV KGFYPSDIAV EWESNGQPEN NYKTTPPMLD SDGSFFLYSK 351LTVDKSRWQQ GNVFSCSVMH EALHNHYTQK SLSLSPGKItem 2 shows a nucleotide sequence encodinghTβRII_(short)(23-159/D110K)-hG2Fc (SEQ ID NO: 26). Double underlineindicates D110K substitution. Dotted underline denotes leader, and solidunderline denotes linker.

(SEQ ID NO: 26)   1

 51

 101 TTAATAACGA CATGATAGTC ACTGACAACA ACGGTGCAGT CAAGTTTCCA  151CAACTGTGTA AATTTTGTGA TGTGAGATTT TCCACCTGTG ACAACCAGAA  201ATCCTGCATG AGCAACTGCA GCATCACCTC CATCTGTGAG AAGCCACAGG  251AAGTCTGTGT GGCTGTATGG AGAAAGAATG ACGAGAACAT AACACTAGAG  301ACAGTTTGCC ATGACCCCAA GCTCCCCTAC CATAAGTTTA TTCTGGAAGA  351TGCTGCTTCT CCAAAGTGCA TTATGAAGGA AAAAAAAAAG CCTGGTGAGA  401CTTTCTTCAT GTGTTCCTGT AGCTCTGATG AGTGCAATGA CAACATCATC  451TTCTCAGAAG AATATAACAC CAGCAATCCT GACACCGGTG GTGGAGTCGA  501GTGCCCACCG TGCCCAGCAC CACCTGTGGC AGGACCGTCA GTCTTCCTCT  551TCCCCCCAAA ACCCAAGGAC ACCCTCATGA TCTCCCGGAC CCCTGAGGTC  601ACGTGCGTGG TGGTGGACGT GAGCCACGAA GACCCCGAGG TCCAGTTCAA  651CTGGTACGTG GACGGCGTGG AGGTGCATAA TGCCAAGACA AAGCCACGGG  701AGGAGCAGTT CAACAGCACG TTCCGTGTGG TCAGCGTCCT CACCGTCGTG  751CACCAGGACT GGCTGAACGG CAAGGAGTAC AAGTGCAAGG TCTCCAACAA  801AGGCCTCCCA GCCCCCATCG AGAAAACCAT CTCCAAAACC AAAGGGCAGC  851CCCGAGAACC ACAGGTGTAC ACCCTGCCCC CATCCCGGGA GGAGATGACC  901AAGAACCAGG TCAGCCTGAC CTGCCTGGTC AAAGGCTTCT ACCCCAGCGA  951CATCGCCGTG GAGTGGGAGA GCAATGGGCA GCCGGAGAAC AACTACAAGA 1001CCACACCTCC CATGCTGGAC TCCGACGGCT CCTTCTTCCT CTACAGCAAG 1051CTCACCGTGG ACAAGAGCAG GTGGCAGCAG GGGAACGTCT TCTCATGCTC 1101CGTGATGCAT GAGGCTCTGC ACAACCACTA CACGCAGAAG AGCCTCTCCC 1151TGTCTCCGGG TAAAItem 3 shows the amino acid sequence ofhTβRII_(short)(23-159/D110K)-hG1Fc_(short) (SEQ ID NO: 27). Doubleunderline indicates D110K substitution. Dotted underline denotes leader,and solid underline denotes linker.

(SEQ ID NO: 27)   1

 51 QLCKFCDVRF STCDNQKSCM SNCSITSICE KPQEVCVAVW RKNDENITLE 101TVCHDPKLPY HKFILEDAAS PKCIMKEKKK PGETFFMCSC SSDECNDNII 151FSEEYNTSNP DTGGGTHTCP PCPAPELLGG PSVFLFPPKP KDTLMISRTP 201EVTCVVVDVS HEDPEVKFNW YVDGVEVHNA KTKPREEQYN STYRVVSVLT 251VLHQDWLNGK EYKCKVSNKA LPAPIEKTIS KAKGQPREPQ VYTLPPSREE 301MTKNQVSLTC LVKGFYPSDI AVEWESNGQP ENNYKTTPPV LDSDGSFFLY 351SKLTVDKSRW QQGNVFSCSV MHEALHNHYT QKSLSLSPGKItem 4 shows a nucleotide sequence encodinghTβRII_(short)(23-159/D110K)-hG1Fc_(short) (SEQ ID NO: 28). Doubleunderline indicates D110K substitution. Dotted underline denotes leader,and solid underline denotes linker.

(SEQ ID NO: 28)   1

  51

 101 TTAATAACGA CATGATAGTC ACTGACAACA ACGGTGCAGT CAAGTTTCCA  151CAACTGTGTA AATTTTGTGA TGTGAGATTT TCCACCTGTG ACAACCAGAA  201ATCCTGCATG AGCAACTGCA GCATCACCTC CATCTGTGAG AAGCCACAGG  251AAGTCTGTGT GGCTGTATGG AGAAAGAATG ACGAGAACAT AACACTAGAG  301ACAGTTTGCC ATGACCCCAA GCTCCCCTAC CATAAGTTTA TTCTGGAAGA  351TGCTGCTTCT CCAAAGTGCA TTATGAAGGA AAAAAAAAAG CCTGGTGAGA  401CTTTCTTCAT GTGTTCCTGT AGCTCTGATG AGTGCAATGA CAACATCATC  451TTCTCAGAAG AATATAACAC CAGCAATCCT GACACCGGTG GTGGAACTCA  501CACATGCCCA CCGTGCCCAG CACCTGAACT CCTGGGGGGA CCGTCAGTCT  551TCCTCTTCCC CCCAAAACCC AAGGACACCC TCATGATCTC CCGGACCCCT  601GAGGTCACAT GCGTGGTGGT GGACGTGAGC CACGAAGACC CTGAGGTCAA  651GTTCAACTGG TACGTGGACG GCGTGGAGGT GCATAATGCC AAGACAAAGC  701CGCGGGAGGA GCAGTACAAC AGCACGTACC GTGTGGTCAG CGTCCTCACC  751GTCCTGCACC AGGACTGGCT GAATGGCAAG GAGTACAAGT GCAAGGTCTC  801CAACAAAGCC CTCCCAGCCC CCATCGAGAA AACCATCTCC AAAGCCAAAG  851GGCAGCCCCG AGAACCACAG GTGTACACCC TGCCCCCATC CCGGGAGGAG  901ATGACCAAGA ACCAGGTCAG CCTGACCTGC CTGGTCAAAG GCTTCTATCC  951CAGCGACATC GCCGTGGAGT GGGAGAGCAA TGGGCAGCCG GAGAACAACT 1001ACAAGACCAC GCCTCCCGTG CTGGACTCCG ACGGCTCCTT CTTCCTCTAT 1051AGCAAGCTCA CCGTGGACAA GAGCAGGTGG CAGCAGGGGA ACGTCTTCTC 1101ATGCTCCGTG ATGCATGAGG CTCTGCACAA CCACTACACG CAGAAGAGCC 1151TCTCCCTGTC CCCGGGTAAAItem 5 shows the amino acid sequence of hTβRII_(short)(29-159)-hG2Fc(SEQ ID NO: 29). Dotted underline denotes leader, and solid underlinedenotes linker.

(SEQ ID NO: 29)   1

 51 DVRFSTCDNQ KSCMSNCSIT SICEKPQEVC VAVWRKNDEN ITLETVCHDP 101KLPYHDFILE DAASPKCIMK EKKKPGETFF MCSCSSDECN DNIIFSEEYN 151TSNPDTGGGV ECPPCPAPPV AGPSVFLFPP KPKDTLMISR TPEVTCVVVD 201VSHEDPEVQF NWYVDGVEVH NAKTKPREEQ FNSTFRVVSV LTVVHQDWLN 251GKEYKCKVSN KGLPAPIEKT ISKTKGQPRE PQVYTLPPSR EEMTKNQVSL 301TCLVKGFYPS DIAVEWESNG QPENNYKTTP PMLDSDGSFF LYSKLTVDKS 351RWQQGNVFSC SVMHEALHNH YTQKSLSLSP GKItem 6 shows a nucleotide sequence encoding hTβRII_(short)(29-159)-hG2Fc(SEQ ID NO: 30). Dotted underline denotes leader, and solid underlinedenotes linker.

(SEQ ID NO: 30)    1

  51

 101 TCACTGACAA CAACGGTGCA GTCAAGTTTC CACAACTGTG TAAATTTTGT  151GATGTGAGAT TTTCCACCTG TGACAACCAG AAATCCTGCA TGAGCAACTG  201CAGCATCACC TCCATCTGTG AGAAGCCACA GGAAGTCTGT GTGGCTGTAT  251GGAGAAAGAA TGACGAGAAC ATAACACTAG AGACAGTTTG CCATGACCCC  301AAGCTCCCCT ACCATGACTT TATTCTGGAA GATGCTGCTT CTCCAAAGTG  351CATTATGAAG GAAAAAAAAA AGCCTGGTGA GACTTTCTTC ATGTGTTCCT  401GTAGCTCTGA TGAGTGCAAT GACAACATCA TCTTCTCAGA AGAATATAAC  451ACCAGCAATC CTGACACCGG TGGTGGAGTC GAGTGCCCAC CGTGCCCAGC  501ACCACCTGTG GCAGGACCGT CAGTCTTCCT CTTCCCCCCA AAACCCAAGG  551ACACCCTCAT GATCTCCCGG ACCCCTGAGG TCACGTGCGT GGTGGTGGAC  601GTGAGCCACG AAGACCCCGA GGTCCAGTTC AACTGGTACG TGGACGGCGT  651GGAGGTGCAT AATGCCAAGA CAAAGCCACG GGAGGAGCAG TTCAACAGCA  701CGTTCCGTGT GGTCAGCGTC CTCACCGTCG TGCACCAGGA CTGGCTGAAC  751GGCAAGGAGT ACAAGTGCAA GGTCTCCAAC AAAGGCCTCC CAGCCCCCAT  801CGAGAAAACC ATCTCCAAAA CCAAAGGGCA GCCCCGAGAA CCACAGGTGT  851ACACCCTGCC CCCATCCCGG GAGGAGATGA CCAAGAACCA GGTCAGCCTG  901ACCTGCCTGG TCAAAGGCTT CTACCCCAGC GACATCGCCG TGGAGTGGGA  951GAGCAATGGG CAGCCGGAGA ACAACTACAA GACCACACCT CCCATGCTGG 1001ACTCCGACGG CTCCTTCTTC CTCTACAGCA AGCTCACCGT GGACAAGAGC 1051AGGTGGCAGC AGGGGAACGT CTTCTCATGC TCCGTGATGC ATGAGGCTCT 1101GCACAACCAC TACACGCAGA AGAGCCTCTC CCTGTCTCCG GGTAAAItem 7 shows the amino acid sequence ofhTβRII_(short)(29-159)-hG1Fc_(short) (SEQ ID NO: 31). Dotted underlinedenotes leader, and solid underline denotes linker.

(SEQ ID NO: 31)   1

 51 DVRFSTCDNQ KSCMSNCSIT SICEKPQEVC VAVWRKNDEN ITLETVCHDP 101KLPYHDFILE DAASPKCIMK EKKKPGETFF MCSCSSDECN DNIIFSEEYN 151TSNPDTGGGT HTCPPCPAPE LLGGPSVFLF PPKPKDTLMI SRTPEVTCVV 201VDVSHEDPEV KFNWYVDGVE VHNAKTKPRE EQYNSTYRVV SVLTVLHQDW 251LNGKEYKCKV SNKALPAPIE KTISKAKGQP REPQVYTLPP SREEMTKNQV 301SLTCLVKGFY PSDIAVEWES NGQPENNYKT TPPVLDSDGS FFLYSKLTVD 351KSRWQQGNVF SCSVMHEALH NHYTQKSLSL SPGKItem 8 shows a nucleotide sequence encodinghTβRII_(short)(29-159)-hG1Fc_(short) (SEQ ID NO: 32). Dotted underlinedenotes leader, and solid underline denotes linker.

Item 9 shows the amino acid sequence of hTβRII_(short)(35-159)-hG2Fc(SEQ ID NO: 33). Dotted underline denotes leader, and solid underlinedenotes linker.

Item 10 shows a nucleotide sequence encodinghTβRII_(short)(35-159)-hG2Fc (SEQ ID NO: 34). Dotted underline denotesleader, and solid underline denotes linker.

Item 11 shows the amino acid sequence ofhTβRII_(short)(35-159)-hG1Fc_(short) (SEQ ID NO: 35). Dotted underlinedenotes leader, and solid underline denotes linker.

Item 12 shows a nucleotide sequence encodinghTβRII_(short)(35-159)-hG1Fc_(short). (SEQ ID NO: 36). Dotted underlinedenotes leader, and solid underline denotes linker.

Item 13 shows the amino acid sequence of hTβRII_(short)(23-153)-hG2Fc(SEQ ID NO: 37). Dotted underline denotes leader, and solid underlinedenotes linker.

Item 14 shows a nucleotide sequence encodinghTβRII_(short)(23-153)-hG2Fc (SEQ ID NO: 38). Dotted underline denotesleader, and solid underline denotes linker.

Item 15 shows the amino acid sequence ofhTβRII_(short)(23-153)-hG1Fc_(short) (SEQ ID NO: 39). Dotted underlinedenotes leader, and solid underline denotes linker.

Item 16 shows a nucleotide sequence encodinghTβRII_(short)(23-153)-hG1Fc_(short) (SEQ ID NO: 40). Dotted underlinedenotes leader, and solid underline denotes linker.

Item 17 shows the amino acid sequence ofhTβRII_(short)(23-153/N70D)-hG2Fc (SEQ ID NO: 41). Double underlineindicates N70D substitution. Dotted underline denotes leader, and solidunderline denotes linker.

Item 18 shows a nucleotide sequence encodinghTβRII_(short)(23-153/N70D)-hG2Fc (SEQ ID NO: 42). Double underlineindicates N70D substitution. Dotted underline denotes leader, and solidunderline denotes linker.

Item 19 shows the amino acid sequence ofhTβRII_(short)(23-153/N70D)-hG1Fc_(short) (SEQ ID NO: 43). Doubleunderline indicates N70D substitution. Dotted underline denotes leader,and solid underline denotes linker.

Item 20 shows a nucleotide sequence encodinghTβRII_(short)(23-153/N70D)-hG1Fc_(short) (SEQ ID NO: 44). Doubleunderline indicates N70D substitution. Dotted underline denotes leader,and solid underline denotes linker.

Item 21 shows the mature amino acid sequence (i.e., without the leadersequence) of hTβRII_(short)(23-159/D110K)-hG2Fc (SEQ ID NO: 53). Doubleunderline indicates D110K substitution. Single underline denotes linker.

(SEQ ID NO: 53)                           TIPPHV QKSVNNDMIV TDNNGAVKFPQLCKFCDVRF STCDNQKSCM SNCSITSICE KPQEVCVAVW RKNDENITLE TVCHDPKLPYHKFILEDAAS PKCIMKEKKK PGETFFMCSC SSDECNDNII FSEEYNTSNP DTGGGVECPPCPAPPVAGPS VFLFPPKPKD TLMISRTPEV TCVVVDVSHE DPEVQFNWYV DGVEVHNAKTKPREEQFNST FRVVSVLTVV HQDWLNGKEY KCKVSNKGLP APIEKTISKT KGQPREPQVYTLPPSREEMT KNQVSLTCLV KGFYPSDIAV EWESNGQPEN NYKTTPPMLD SDGSFFLYSKLTVDKSRWQQ GNVFSCSVMH EALHNHYTQK SLSLSPGKItem 22 shows the mature amino acid sequence (i.e., without the leadersequence) of hTβRII_(short)(23-159/D110K)-hG1Fc_(short) (SEQ ID NO: 54).Double underline indicates D110K substitution. Single underline denoteslinker.

(SEQ ID NO: 54)                           TIPPHV QKSVNNDMIV TDNNGAVKFPQLCKFCDVRF STCDNQKSCM SNCSITSICE KPQEVCVAVW RKNDENITLE TVCHDPKLPYHKFILEDAAS PKCIMKEKKK PGETFFMCSC SSDECNDNII FSEEYNTSNP DTGGGTHTCPPCPAPELLGG PSVFLFPPKP KDTLMISRTP EVTCVVVDVS HEDPEVKFNW YVDGVEVHNAKTKPREEQYN STYRVVSVLT VLHQDWLNGK EYKCKVSNKA LPAPIEKTIS KAKGQPREPQVYTLPPSREE MTKNQVSLTC LVKGFYPSDI AVEWESNGQP ENNYKTTPPV LDSDGSFFLYSKLTVDKSRW QQGNVFSCSV MHEALHNHYT QKSLSLSPGKItem 23 shows the mature amino acid sequence (i.e., without the leadersequence) of hTβRII_(short)(29-159)-hG2Fc (SEQ ID NO: 55). Singleunderline denotes linker.

(SEQ ID NO: 55)                           QKSVNN DMIVTDNNGA VKFPQLCKFCDVRFSTCDNQ KSCMSNCSIT SICEKPQEVC VAVWRKNDEN ITLETVCHDP KLPYHDFILEDAASPKCIMK EKKKPGETFF MCSCSSDECN DNIIFSEEYN TSNPDTGGGV ECPPCPAPPVAGPSVFLFPP KPKDTLMISR TPEVTCVVVD VSHEDPEVQF NWYVDGVEVH NAKTKPREEQFNSTFRVVSV LTVVHQDWLN GKEYKCKVSN KGLPAPIEKT ISKTKGQPRE PQVYTLPPSREEMTKNQVSL TCLVKGFYPS DIAVEWESNG QPENNYKTTP PMLDSDGSFF LYSKLTVDKSRWQQGNVFSC SVMHEALHNH YTQKSLSLSP GKItem 24 shows the mature amino acid sequence (i.e., without the leadersequence) of hTβRII_(short)(29-159)-hG1Fc_(short) (SEQ ID NO: 56).Single underline denotes linker.

(SEQ ID NO: 56)                           QKSVNN DMIVTDNNGA VKFPQLCKFCDVRFSTCDNQ KSCMSNCSIT SICEKPQEVC VAVWRKNDEN ITLETVCHDP KLPYHDFILEDAASPKCIMK EKKKPGETFF MCSCSSDECN DNIIFSEEYN TSNPDTGGGT HTCPPCPAPELLGGPSVFLF PPKPKDTLMI SRTPEVTCVV VDVSHEDPEV KFNWYVDGVE VHNAKTKPREEQYNSTYRVV SVLTVLHQDW LNGKEYKCKV SNKALPAPIE KTISKAKGQP REPQVYTLPPSREEMTKNQV SLTCLVKGFY PSDIAVEWES NGQPENNYKT TPPVLDSDGS FFLYSKLTVDKSRWQQGNVF SCSVMHEALH NHYTQKSLSL SPGKItem 25 shows the mature amino acid sequence (i.e., without the leadersequence) of hTβRII_(short)(35-159)-hG2Fc (SEQ ID NO: 57). Singleunderline denotes linker.

(SEQ ID NO: 57)                           DMIVTD NNGAVKFPQL CKFCDVRFSTCDNQKSCMSN CSITSICEKP QEVCVAVWRK NDENITLETV CHDPKLPYHD FILEDAASPKCIMKEKKKPG ETFFMCSCSS DECNDNIIFS EEYNTSNPDT GGGVECPPCP APPVAGPSVFLFPPKPKDTL MISRTPEVTC VVVDVSHEDP EVQFNWYVDG VEVHNAKTKP REEQFNSTFRVVSVLTVVHQ DWLNGKEYKC KVSNKGLPAP IEKTISKTKG QPREPQVYTL PPSREEMTKNQVSLTCLVKG FYPSDIAVEW ESNGQPENNY KTTPPMLDSD GSFFLYSKLT VDKSRWQQGNVFSCSVMHEA LHNHYTQKSL SLSPGKItem 26 shows the mature amino acid sequence (i.e., without the leadersequence) of hTβRII_(short)(35-159)-hG1Fc_(short) (SEQ ID NO: 58).Single underline denotes linker.

(SEQ ID NO: 58)                           DMIVTD NNGAVKFPQL CKFCDVRFSTCDNQKSCMSN CSITSICEKP QEVCVAVWRK NDENITLETV CHDPKLPYHD FILEDAASPKCIMKEKKKPG ETFFMCSCSS DECNDNIIFS EEYNTSNPDT GGGTHTCPPC PAPELLGGPSVFLFPPKPKD TLMISRTPEV TCVVVDVSHE DPEVKFNWYV DGVEVHNAKT KPREEQYNSTYRVVSVLTVL HQDWLNGKEY KCKVSNKALP APIEKTISKA KGQPREPQVY TLPPSREEMTKNQVSLTCLV KGFYPSDIAV EWESNGQPEN NYKTTPPVLD SDGSFFLYSK LTVDKSRWQQGNVFSCSVMH EALHNHYTQK SLSLSPGKItem 27 shows the mature amino acid sequence (i.e., without the leadersequence) of hTβRII_(short)(23-153)-hG2Fc (SEQ ID NO: 59). Singleunderline denotes linker.

(SEQ ID NO: 59)                           TIPPHV QKSVNNDMIV TDNNGAVKFPQLCKFCDVRF STCDNQKSCM SNCSITSICE KPQEVCVAVW RKNDENITLE TVCHDPKLPYHDFILEDAAS PKCIMKEKKK PGETFFMCSC SSDECNDNII FSEEYTGGGV ECPPCPAPPVAGPSVFLFPP KPKDTLMISR TPEVTCVVVD VSHEDPEVQF NWYVDGVEVH NAKTKPREEQFNSTFRVVSV LTVVHQDWLN GKEYKCKVSN KGLPAPIEKT ISKTKGQPRE PQVYTLPPSREEMTKNQVSL TCLVKGFYPS DIAVEWESNG QPENNYKTTP PMLDSDGSFF LYSKLTVDKSRWQQGNVFSC SVMHEALHNH YTQKSLSLSP GKItem 28 shows the mature amino acid sequence (i.e., without the leadersequence) of hTβRII_(short)(23-153)-hG1Fc_(short) (SEQ ID NO: 60).Single underline denotes linker.

(SEQ ID NO: 60)                           TIPPHV QKSVNNDMIV TDNNGAVKFPQLCKFCDVRF STCDNQKSCM SNCSITSICE KPQEVCVAVW RKNDENITLE TVCHDPKLPYHDFILEDAAS PKCIMKEKKK PGETFFMCSC SSDECNDNII FSEEYTGGGT HTCPPCPAPELLGGPSVFLF PPKPKDTLMI SRTPEVTCVV VDVSHEDPEV KFNWYVDGVE VHNAKTKPREEQYNSTYRVV SVLTVLHQDW LNGKEYKCKV SNKALPAPIE KTISKAKGQP REPQVYTLPPSREEMTKNQV SLTCLVKGFY PSDIAVEWES NGQPENNYKT TPPVLDSDGS FFLYSKLTVDKSRWQQGNVF SCSVMHEALH NHYTQKSLSL SPGKItem 29 shows the mature amino acid sequence (i.e., without the leadersequence) of hTβRII_(short)(23-153/N70D)-hG2Fc (SEQ ID NO: 61). Doubleunderline indicates N70D substitution. Single underline denotes linker.

(SEQ ID NO: 61)                           TIPPHV QKSVNNDMIV TDNNGAVKFPQLCKFCDVRF STCDNQKSCM SDCSITSICE KPQEVCVAVW RKNDENITLE TVCHDPKLPYHDFILEDAAS PKCIMKEKKK PGETFFMCSC SSDECNDNII FSEEYTGGGV ECPPCPAPPVAGPSVFLFPP KPKDTLMISR TPEVTCVVVD VSHEDPEVQF NWYVDGVEVH NAKTKPREEQFNSTFRVVSV LTVVHQDWLN GKEYKCKVSN KGLPAPIEKT ISKTKGQPRE PQVYTLPPSREEMTKNQVSL TCLVKGFYPS DIAVEWESNG QPENNYKTTP PMLDSDGSFF LYSKLTVDKSRWQQGNVFSC SVMHEALHNH YTQKSLSLSP GKItem 30 shows the mature amino acid sequence (i.e., without the leadersequence) of hTβRII_(short)(23-153/N70D)-hG1Fc_(short) (SEQ ID NO: 62).Double underline indicates N70D substitution. Single underline denoteslinker.

(SEQ ID NO: 62)                           TIPPHV QKSVNNDMIV TDNNGAVKFPQLCKFCDVRF STCDNQKSCM SDCSITSICE KPQEVCVAVW RKNDENITLE TVCHDPKLPYHDFILEDAAS PKCIMKEKKK PGETFFMCSC SSDECNDNII FSEEYTGGGT HTCPPCPAPELLGGPSVFLF PPKPKDTLMI SRTPEVTCVV VDVSHEDPEV KFNWYVDGVE VHNAKTKPREEQYNSTYRVV SVLTVLHQDW LNGKEYKCKV SNKALPAPIE KTISKAKGQP REPQVYTLPPSREEMTKNQV SLTCLVKGFY PSDIAVEWES NGQPENNYKT TPPVLDSDGS FFLYSKLTVDKSRWQQGNVF SCSVMHEALH NHYTQKSLSL SPGK

Example 4 Effects of TβRII-Fc in a JAK2V617F Animal Model

Myeloproliferative disorders are a group of conditions characterized, inpart, by blood cells abnormalities (e.g., abnormal levels of one or moreof platelets, white blood cells, and red blood cells). This group ofdisorders includes polycythemia vera (PV), essential thrombocythemia(ET), and myelofibrosis (MF). Recently, several groups identified again-of-function mutation of tyrosine kinase JAK2 (JAK2V617F) as a majormolecular defect in patients with PV, ET, and MF [e.g., Kralovics et al(2005) N Engl J Med 2005; 352:1779-1790]. The mutation results inconstitutive activation of JAK2, which has been associated withdevelopment or worsening of myeloproliferative disease. Recently a JAK2inhibitor (ruxolitinib) has been approved for treatment of MF and PV.

A JAK2V617F myeloproliferative disease model has been developed thatclosely resembles human neoplasms [Xing et al. (2008) Blood 111:5109-5117]. In particular, JAK2V617F mice develop pathology that closelyresembles human PV or ET at a young age, and the disease progresses withadvanced age, resulting in myelofibrosis. Applicants have evaluated theeffects of a TβRII_(long)-Fc fusion protein in this JAK2V617F model ofmyeloproliferative disease.

Transgenic JAK2V617F mutant mice [the A line as described in Xing et al.(2008) Blood 111: 5109-5117] and age-matched wild-type (control) mice(C57BL/6 mice) were used in these studies. To understand the onset andprogression of myelofibrosis disease, the complete blood counts anddegree of fibrosis in JAK2V617F mice was compared, at various ages, todata obtained from control animals. Red blood cell (RBC) and plateletlevels were elevated in JAK2V617F mice at all ages compared towild-type, with a trend toward increased levels in mutant animalsbetween 2 to 5 months followed by a progressive decrease between 8 to 14months. Fibrosis was detectable in bone marrow of JAK2V617F micestarting around 5 months, which worsened with age. JAK2V617F mice alsodisplayed splenomegaly, which also worsened with age. Interestingly,serum levels of TGFβ1, TGFβ2, and various bone metabolic cytokines(e.g., OPG, OPN, aFGF, and Trance) were more elevated in youngerJAK2V617F mice (2-5 months) than in older JAK2V617F mice, whichcoincides with the observed increase in RBC and platelet levels. Peakserum levels of these proteins were observed at the onset of fibrosis(around 5 months). Similarly, inflammatory cytokines (e.g., IL-6, IL-1b,and TNFα) were elevated at older ages. Accordingly, JAK2V617F micedisplay PV or ET pathology at an early age (approximately 2-5 months ofage) and develop MF pathology as they age (after approximately 5-8months of age).

For the TβRII-Fc study, treatment was initiated at 4 months of age,which corresponds to elevated serum TGFβ1 but prior to the onset offibrosis (at around 5 months of age). Mice were placed into one of threegroups: i) treatment of JAK2V617F mice with murine (mTβRII-Fc), asdescribed above, on a dosing schedule of 10 mg/kg twice weekly; ii)treatment of JAK2V617F mice with vehicle (TBS) twice weekly; and iii)vehicle treated wild-type mice (C57BL/6 mice). Following 6 months oftreatment, vehicle treated JAK2V617F mice displayed elevated RBC levels(+37.1%, P<0.001), elevated platelets (+74.5%, P<0.001), and increasedspleen weights (+9.5-fold, P<0.001) compared to wild-type mice. Inaddition, bone marrow sections from vehicle treated JAK2V617F mice (seeFIG. 4B) revealed severe fibrosis compared to wild-type mice (see FIG.4A). In comparison to vehicle, mTβRII-Fc JAK2V617F mice trended towardlower RBC levels (see FIG. 5A), and flow-cytometric analysis revealedreduced levels of Ter119+erythroid precursor cells in bone marrow andspleen samples (−15%, P<0.05). Treatment also had a significant effecton splenomegaly, with mTβRII-Fc treated JAK2V617F mice having reducedspleen weights (−29%, P<0.01) compared to vehicle treatment (FIG. 5B),and fibrosis, with mTβRII-Fc treated JAK2V617F mice having reduced bonemarrow fibrosis (see FIG. 4C) and spleen fibrosis compared to vehicletreatment (see FIGS. 6A and 6B). Consistent with the reduction infibrosis, mTβRII-Fc treated JAK2V617F mice displayed reduced IL-6 levels(−48.9%, P<0.05) compared to vehicle treated mice.

Accordingly, the data show that high serum TGFβ levels are correlatedwith the onset fibrosis in this JAK2V617F disease model (around 5 monthsof age) and that treatment with a TβRII-Fc fusion protein results inreduction of fibrosis and splenomegaly as well as other morbiditiesassociated with the disease (e.g., reduced levels of inflammatorycytokines). Together, these data demonstrate that TβRII-Fc polypeptidesmay be used to treat or prevent disease resultant from the JAK2V617Fmutation, which indicates that such therapeutics may be used to treatmyeloproliferative disorders (e.g., polycythemia vera, essentialthrombocythaemia, and primary myelofibrosis, post-polycythemia vera, andpost-essential thrombocythaemia) and other Janus-kinase associateddisorders. In view of the positive effects on early (e.g., splenomegalyand elevated blood cell levels) and late (e.g., fibrosis andproinflammatory cytokines) stage disease pathology, TβRII-Fcpolypeptides may be particular well suited for treatment of PV, ET, andMF patients. For example, TβRII-Fc treatment mitigates PV and ETpathologies as well as prevents the onset/delays or reduces the severityof fibrosis and other late stage disease complications. TβRII-Fctreatment may also be useful in preventing/delaying the transition of PVand/or ET into secondary myelofibrosis disease (post-polycythemia veramyelofibrosis and post-essential thrombocythaemia myelofibrosis).

Example 5 Effects of TβRII-Fc and Ruxolitinib in a JAK2V617F AnimalModel

The transgenic JAK2V617F mutant mice model described above was furtherused to compare the effects of mTβRII-Fc and ruxolitinib (nix),separately and in combination, on myelofibrosis. In contrast to Example4, treatment in this study was initiated at 12 months of age, whichcorresponds to a late stage of myelofibrosis in which mice generallyhave increased levels of fibrosis in various tissues (e.g., the bonemarrow and spleen) and reduced red blood cell levels in comparison toyounger JAK2V617 mice (e.g., 2-5 months old). Mice were placed into oneof four groups: i) treatment of JAK2V617F mice with vehicle (TBS) twiceweekly; ii) treatment of JAK2V617F mice with mTβRII-Fc, as describedabove, on a dosing schedule of 10 mg/kg twice weekly; iii) treatment ofJAK2V617F mice with Tux on a dosing schedule of 60 mg/kg twice daily;and iv) treatment of JAK2V617F mice with mTβRII-Fc at 10 mg/kg twiceweekly and Tux at 60 mg/kg daily. After three weeks of treatment, nixtreatment alone or in combination with mTβRII-Fc significantly loweredRBC levels and reduced spleen weights compared to vehicle treated mice(see FIGS. 7A and 7B). mTβRII-Fc treatment alone had a more modesteffect on RBC levels and spleen weights in the older JAK2V617F mice.Bone marrow fibrosis was also assessed after three weeks of treatment.Rux and vehicle treated mice had similar, high levels of bone marrowfibrosis, which is consistent with the observation that nix does notappear to improve bone marrow fibrosis in human patients (see FIGS. 8Band 8A, respectively). Surprisingly, mTβRII-Fc treatment alone or incombination with nix appears to reduce bone marrow fibrosis within atleast as early as three weeks after starting therapy (see FIGS. 8C and8D, respectively), suggesting that mTβRII-Fc treatment may actuallyreverse fibrotic scaring in patients with advanced myelofibrosis.

As demonstrated by the data, myelofibrosis is a complex disease in whichpatients are afflicted with many different complications including, forexample, erythroid hyperplasia, splenomegaly, increased inflammatorycytokine levels, and tissue fibrosis. Rux is currently an approvedtherapeutic for treating myelofibrosis. While nix has been shown toreduce splenomegaly, it does not treat other complications of thedisease including, for example, bone marrow fibrosis. In both the earlyand late stage myelofibrosis studies, Applicants have demonstrated thattreatment with a TβRII-Fc fusion protein alone may be used to decreasetissue fibrosis and have other positive effects on myeloproliferativedisease (e.g., reduction of splenomegaly and blood cell levels,particularly in PV and ET stages of the disease). TβRII antagonisttreatment therefore has beneficial effects on treating certaincomplications of myelofibrosis which are not affected by nix.Accordingly, Applicants have demonstrated that a TβRII-Fc fusion proteinmay be used as a monotherapy, as well as a co-therapy with nix, to treatmyelofibrosis as well as Janus kinase-associated disorders. Moreover,these data suggest that TβRII antagonist may have various beneficialeffects in treating, preventing, or reducing the progression rate and/orseverity of myeloproliferative disorders, particularly in treating,preventing, or reducing the progression rate and/or severity of one ormore complications of a MF, PV, and/or ET.

INCORPORATION BY REFERENCE

All publications and patents mentioned herein are hereby incorporated byreference in their entirety as if each individual publication or patentwas specifically and individually indicated to be incorporated byreference.

While specific embodiments of the subject matter have been discussed,the above specification is illustrative and not restrictive. Manyvariations will become apparent to those skilled in the art upon reviewof this specification and the claims below. The full scope of theinvention should be determined by reference to the claims, along withtheir full scope of equivalents, and the specification, along with suchvariations.

1. A method for treating a Janus kinase-associated disorder, comprisingadministering to a patient in need thereof an effective amount of aTβRII antagonist.
 2. A method for treating a Janus-kinase disorder,comprising administering to a patient in need thereof: i) a TβRIIantagonist and ii) a Janus kinase inhibitor, wherein the TβRIIantagonist and Janus kinase inhibitor are administered in an effectiveamount.
 3. (canceled)
 4. The method of claim 1, wherein the TβRIIantagonist inhibits TGFβ1 and TGFβ3.
 5. The method of claim 1, whereinthe TβRII antagonist is a TβRII polypeptide.
 6. The method of claim 5,wherein the TβRII polypeptide is an Fc fusion protein.
 7. The method ofclaim 6, wherein the TβRII-Fc fusion protein comprises the amino acidsequence of SEQ ID NO:
 103. 8. The method of claim 1, wherein thepatient has a disorder associated with a gain-of-function Janus kinasemutation.
 9. The method of claim 8, wherein the patient has a disorderassociated with a gain-of-function Janus kinase mutation in one or moreJanus kinases selected from the group consisting of: JAK1, JAK2, andJAK3.
 10. The method of claim 9, wherein the patient has a disorderassociated with a gain-of-function mutation in JAK2.
 11. The method ofclaim 1, wherein the patient has a disorder associated with constitutivekinase activity of one or more Janus kinases.
 12. The method of claim11, wherein the patient has a disorder associated with constitutivekinase activity of one or more Janus kinases selected from the groupconsisting of: JAK1, JAK2, and JAK3.
 13. The method of claim 12, whereinthe patient has a disorder associated with constitutive kinase activityof JAK2.
 14. The method of claim 1, wherein the patient has aJAK2-associated disorder.
 15. The method of claim 14, wherein thepatient has a JAK2V617F-associated disorder.
 16. (canceled)
 17. Themethod of claim 1, wherein the patient has myelofibrosis.
 18. The methodof claim 17, wherein the patient has primary myelofibrosis.
 19. Themethod of claim 17, wherein the patient has post-polycythemia veramyelofibrosis.
 20. The method of claim 17, wherein the patient haspost-essential thrombocythemia myelofibrosis. 21-26. (canceled)
 27. Themethod of claim 1, wherein the patient has polycythemia vera. 28-35.(canceled)
 36. The method of claim 1, wherein the patient has essentialthrombocythemia. 37-89. (canceled)
 90. The method of claim 1, whereinthe patient is being treated with or has been treated with a Januskinase inhibitor.
 91. The method of claim 90, wherein the patient isintolerant or refractory to treatment with a Janus kinase inhibitor. 92.The method of claim 90, wherein the Janus kinase inhibitor inhibits atleast JAK2.
 93. The method of claim 90, wherein the Janus kinaseinhibitor is selected from the group consisting of: ruxolitinib,fedratinib (SAR302503), monoelotinib (CYT387), pacritinib, lestaurtinib,AZD-1480, BMS-911543, NS-018, LY2784544, SEP-701, XL019, and AT-9283.94. The method of claim 93, wherein the Janus kinase inhibitor isruxolitinib. 95-239. (canceled)
 240. The method of claims 5-7, whereinthe TβRII polypeptide comprises one or more modified amino acid residuesselected from: a glycosylated amino acid, a PEGylated amino acid, afarnesylated amino acid, an acetylated amino acid, a biotinylated aminoacid, an amino acid conjugated to a lipid moiety, and an amino acidconjugated to an organic derivatizing agent.
 241. The method of claim240, wherein the TβRII polypeptide is glycosylated.
 242. The method ofclaim 241, wherein the TβRII polypeptide is glycosylated and has aglycosylation pattern obtainable from expression in a CHO cell.
 243. Themethod of claims 5-7, wherein the TβRII polypeptide binds to TGFβ1. 244.The method of claims 5-7, wherein the TβRII polypeptide binds to TGFβ3.245. The method of claims 5-7, wherein the TβRII polypeptide binds toTGFβ1 and TGFβ3.
 246. (canceled)
 247. The method of claims 5-7, whereinthe TβRII polypeptide is isolated.
 248. The method of claims 5-7,wherein the TβRII polypeptide is recombinant. 249-262. (canceled) 263.The method of claim 6 or 7, wherein the fusion protein is a homodimer.